\u8bb8\u591a\u6570\u636e\u5e93\u8bbe\u8ba1\u4f1a\u6839\u636e\u7279\u5b9a\u6570\u636e\u70b9\u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u5c06\u4fe1\u606f\u5206\u79bb\u5230\u4e0d\u540c\u7684\u8868\u4e2d\u3002\u5373\u4f7f\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4e5f\u53ef\u80fd\u51fa\u73b0\u9700\u8981\u540c\u65f6\u4ece\u591a\u4e2a\u8868\u4e2d\u68c0\u7d22\u4fe1\u606f\u7684\u60c5\u51b5\u3002.<\/p>\n
\u5728\u7ed3\u6784\u5316\u67e5\u8be2\u8bed\u8a00 (SQL) \u64cd\u4f5c\u4e2d\uff0c\u8bbf\u95ee\u591a\u4e2a\u8868\u4e2d\u7684\u6570\u636e\u901a\u5e38\u4f7f\u7528 JOIN \u5b50\u53e5\u5c06\u8868\u8fde\u63a5\u8d77\u6765\u3002JOIN \u5b50\u53e5\u57fa\u4e8e\u5173\u7cfb\u4ee3\u6570\u4e2d\u7684\u8fde\u63a5\u64cd\u4f5c\uff0c\u901a\u8fc7\u5339\u914d\u6bcf\u4e2a\u8868\u4e2d\u5f7c\u6b64\u76f8\u5173\u7684\u884c\u6765\u8fde\u63a5\u4e0d\u540c\u7684\u8868\u3002\u901a\u5e38\uff0c\u8fd9\u79cd\u5173\u7cfb\u57fa\u4e8e\u4e00\u5bf9\u5217\uff08\u6bcf\u4e2a\u8868\u4e2d\u5404\u4e00\u5217\uff09\u5171\u4eab\u503c\uff0c\u4f8b\u5982\u4e00\u4e2a\u8868\u7684\u5916\u952e\u548c\u8be5\u5916\u952e\u5f15\u7528\u7684\u53e6\u4e00\u4e2a\u8868\u7684\u4e3b\u952e\u3002.<\/p>\n
\u672c\u6307\u5357\u89e3\u91ca\u4e86\u5982\u4f55\u6784\u5efa\u5305\u542b JOIN \u5b50\u53e5\u7684\u5404\u79cd SQL \u67e5\u8be2\u3002\u5b83\u8fd8\u5c55\u793a\u4e86\u4e0d\u540c\u7c7b\u578b\u7684 JOIN \u5b50\u53e5\u3001\u5982\u4f55\u5408\u5e76\u6765\u81ea\u591a\u4e2a\u8868\u7684\u6570\u636e\uff0c\u4ee5\u53ca\u5982\u4f55\u4e3a\u5217\u521b\u5efa\u522b\u540d\u4ee5\u7b80\u5316 JOIN \u64cd\u4f5c\u7684\u7f16\u5199\u3002.<\/p>\n
\u8981\u9075\u5faa\u672c\u6307\u5357\uff0c\u60a8\u9700\u8981\u4e00\u53f0\u5b89\u88c5\u4e86\u67d0\u79cd\u4f7f\u7528 SQL \u7684\u5173\u7cfb\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf (RDBMS) \u7684\u8ba1\u7b97\u673a\u3002\u672c\u6307\u5357\u4e2d\u7684\u8bf4\u660e\u548c\u793a\u4f8b\u5df2\u5728\u4ee5\u4e0b\u73af\u5883\u4e0b\u9a8c\u8bc1\uff1a<\/p>\n
\u5982\u679c\u60a8\u7684 SQL \u6570\u636e\u5e93\u7cfb\u7edf\u8fd0\u884c\u5728\u8fdc\u7a0b\u670d\u52a1\u5668\u4e0a\uff0c\u8bf7\u4ece\u672c\u5730\u8ba1\u7b97\u673a\u901a\u8fc7 SSH \u8fde\u63a5\u5230\u60a8\u7684\u670d\u52a1\u5668\uff1a<\/p>\n
ssh sammy@your_server_ip\r\n<\/code><\/pre>\n<\/div>\n\u7136\u540e\u6253\u5f00 MySQL \u670d\u52a1\u5668\u63d0\u793a\u7b26\uff0c\u5e76\u5c06 Sami \u66ff\u6362\u4e3a\u60a8\u7684 MySQL \u7528\u6237\u540d\uff1a<\/p>\n
\nmysql -u sammy -p\r\n<\/code><\/pre>\n<\/div>\n\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a joinsDB \u7684\u6570\u636e\u5e93\uff1a<\/p>\n
\nCREATE DATABASE joinsDB;\r\n<\/code><\/pre>\n<\/div>\n\u5982\u679c\u6570\u636e\u5e93\u521b\u5efa\u6210\u529f\uff0c\u60a8\u5c06\u6536\u5230\u4ee5\u4e0b\u8f93\u51fa\uff1a<\/p>\n
\nOutput\r\nQuery OK, 1 row affected (0.01 sec)<\/code><\/pre>\n<\/div>\n\u8981\u9009\u62e9 joinsDB \u6570\u636e\u5e93\uff0c\u8bf7\u8fd0\u884c\u4ee5\u4e0b USE \u8bed\u53e5\uff1a<\/p>\n
\nUSE joinsDB;<\/code><\/pre>\n<\/div>\n\nOutput\r\nDatabase changed<\/code><\/pre>\n<\/div>\n\u9009\u62e9 joinsDB \u540e\uff0c\u5728\u5176\u4e2d\u521b\u5efa\u51e0\u4e2a\u8868\u3002\u5728\u672c\u6307\u5357\u7684\u793a\u4f8b\u793a\u4f8b\u4e2d\uff0c\u5047\u8bbe\u60a8\u7ecf\u8425\u4e00\u5bb6\u5de5\u5382\uff0c\u5e76\u51b3\u5b9a\u5728 SQL \u6570\u636e\u5e93\u4e2d\u8ddf\u8e2a\u6709\u5173\u751f\u4ea7\u7ebf\u3001\u9500\u552e\u56e2\u961f\u5458\u5de5\u548c\u516c\u53f8\u9500\u552e\u60c5\u51b5\u7684\u4fe1\u606f\u3002\u60a8\u5c06\u4ece\u4e09\u4e2a\u8868\u5f00\u59cb\uff0c\u7b2c\u4e00\u4e2a\u8868\u5c06\u5b58\u50a8\u6709\u5173\u4ea7\u54c1\u7684\u4fe1\u606f\u3002\u60a8\u51b3\u5b9a\u7b2c\u4e00\u4e2a\u8868\u9700\u8981\u4e09\u5217\uff1a<\/p>\n
\n- \u4ea7\u54c1 ID\uff1a\u6bcf\u4e2a\u4ea7\u54c1\u7684\u8bc6\u522b\u7f16\u53f7\uff0c\u6570\u636e\u7c7b\u578b\u4e3a int\u3002\u6b64\u5217\u4f5c\u4e3a\u8868\u7684\u4e3b\u952e\uff0c\u8fd9\u610f\u5473\u7740\u6bcf\u4e2a\u503c\u90fd\u4f5c\u4e3a\u5bf9\u5e94\u884c\u7684\u552f\u4e00\u6807\u8bc6\u7b26\u3002\u7531\u4e8e\u4e3b\u952e\u4e2d\u7684\u6bcf\u4e2a\u503c\u90fd\u5fc5\u987b\u552f\u4e00\uff0c\u56e0\u6b64\u8be5\u5217\u8fd8\u5e94\u7528\u4e86 UNIQUE \u7ea6\u675f\u3002<\/li>\n
- productName\uff1a\u6bcf\u4e2a\u4ea7\u54c1\u7684\u540d\u79f0\u4f7f\u7528 varchar \u6570\u636e\u7c7b\u578b\u8868\u793a\uff0c\u6700\u591a 20 \u4e2a\u5b57\u7b26\u3002.<\/li>\n
- \u4ef7\u683c\uff1a\u6bcf\u4ef6\u4ea7\u54c1\u7684\u4ef7\u683c\uff0c\u4ee5\u5341\u8fdb\u5236\u6570\u636e\u7c7b\u578b\u8868\u793a\u3002\u8fd9\u610f\u5473\u7740\u6b64\u5217\u4e2d\u7684\u6bcf\u4e2a\u503c\u6700\u591a\u53ea\u80fd\u5305\u542b\u56db\u4f4d\u6570\u5b57\uff0c\u5176\u4e2d\u4e24\u4f4d\u6570\u5b57\u4f4d\u4e8e\u5c0f\u6570\u70b9\u53f3\u4fa7\u3002\u56e0\u6b64\uff0c\u6b64\u5217\u7684\u53d6\u503c\u8303\u56f4\u4e3a -99.99 \u81f3 99.99\u3002<\/li>\n<\/ul>\n
\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a products \u7684\u8868\uff0c\u8be5\u8868\u5305\u542b\u4ee5\u4e0b\u4e09\u5217\uff1a<\/p>\n
\nCREATE TABLE products (\r\nproductID int UNIQUE,\r\nproductName varchar(20),\r\nprice decimal (4,2),\r\nPRIMARY KEY (productID)\r\n);<\/code><\/pre>\n<\/div>\n\u7b2c\u4e8c\u5f20\u8868\u5b58\u50a8\u4e86\u516c\u53f8\u9500\u552e\u56e2\u961f\u5458\u5de5\u7684\u4fe1\u606f\u3002\u60a8\u51b3\u5b9a\u8fd9\u5f20\u8868\u4e5f\u9700\u8981\u4e09\u5217\uff1a<\/p>\n
\n- empID\uff1a\u4e0e productID \u5217\u7c7b\u4f3c\uff0c\u6b64\u5217\u5305\u542b\u9500\u552e\u56e2\u961f\u4e2d\u6bcf\u4f4d\u5458\u5de5\u7684\u552f\u4e00\u6807\u8bc6\u53f7\uff0c\u6570\u636e\u7c7b\u578b\u4e3a int\u3002\u56e0\u6b64\uff0c\u6b64\u5217\u5c06\u5177\u6709 UNIQUE \u7ea6\u675f\uff0c\u5e76\u5c06\u4f5c\u4e3a\u56e2\u961f\u8868\u7684\u4e3b\u952e\u3002.<\/li>\n
- empName\uff1a\u6bcf\u4e2a\u9500\u552e\u4eba\u5458\u7684\u59d3\u540d\uff0c\u4f7f\u7528 varchar \u6570\u636e\u7c7b\u578b\u8868\u793a\uff0c\u6700\u591a 20 \u4e2a\u5b57\u7b26\u3002.<\/li>\n
- \u4ea7\u54c1\u4e13\u957f\uff1a\u60a8\u7684\u9500\u552e\u56e2\u961f\u4e2d\u7684\u6bcf\u4f4d\u6210\u5458\u90fd\u88ab\u5206\u914d\u4e86\u4e00\u4e2a\u4e13\u957f\u4ea7\u54c1\u3002\u4ed6\u4eec\u53ef\u4ee5\u9500\u552e\u516c\u53f8\u751f\u4ea7\u7684\u4efb\u4f55\u4ea7\u54c1\uff0c\u4f46\u4ed6\u4eec\u7684\u4e3b\u8981\u5de5\u4f5c\u91cd\u5fc3\u662f\u4ed6\u4eec\u4e13\u957f\u7684\u4ea7\u54c1\u3002\u4e3a\u4e86\u5728\u8868\u683c\u4e2d\u4f53\u73b0\u8fd9\u4e00\u70b9\uff0c\u60a8\u9700\u8981\u521b\u5efa\u6b64\u5217\uff0c\u5176\u4e2d\u5305\u542b\u6bcf\u4f4d\u5458\u5de5\u4e13\u957f\u4ea7\u54c1\u7684 productID \u503c\u3002.<\/li>\n<\/ul>\n
\u4e3a\u4e86\u786e\u4fdd productSpecialty \u5217\u4ec5\u5305\u542b\u4ee3\u8868\u6709\u6548\u4ea7\u54c1 ID \u53f7\u7684\u503c\uff0c\u60a8\u51b3\u5b9a\u5bf9\u5f15\u7528 Products \u8868\u4e2d productID \u5217\u7684\u5217\u5e94\u7528\u5916\u952e\u7ea6\u675f\u3002\u5916\u952e\u7ea6\u675f\u662f\u4e00\u79cd\u8868\u8fbe\u4e24\u4e2a\u8868\u4e4b\u95f4\u5173\u7cfb\u7684\u65b9\u6cd5\uff0c\u5b83\u8981\u6c42\u88ab\u7ea6\u675f\u5217\u4e2d\u7684\u503c\u5fc5\u987b\u5b58\u5728\u4e8e\u88ab\u7ea6\u675f\u5217\u4e2d\u3002\u5728\u4e0b\u9762\u7684 CREATE TABLE \u8bed\u53e5\u4e2d\uff0c\u5916\u952e\u7ea6\u675f\u8981\u6c42\u6dfb\u52a0\u5230 team \u8868\u4e2d productSpecialty \u5217\u7684\u4efb\u4f55\u503c\u90fd\u5fc5\u987b\u5b58\u5728\u4e8e Products \u8868\u4e2d productID \u5217\u4e2d\u3002.<\/p>\n
\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a\u201c\u56e2\u961f\u201d\u7684\u8868\u683c\uff0c\u5305\u542b\u4ee5\u4e0b\u4e09\u5217\uff1a<\/p>\n
\nCREATE TABLE team (\r\nempID int UNIQUE,\r\nempName varchar(20),\r\nproductSpecialty int,\r\nPRIMARY KEY (empID),\r\nFOREIGN KEY (productSpecialty) REFERENCES products (productID)\r\n);\r\n<\/code><\/pre>\n<\/div>\n\u60a8\u521b\u5efa\u7684\u6700\u540e\u4e00\u4e2a\u8868\u5c06\u4fdd\u5b58\u516c\u53f8\u7684\u9500\u552e\u8bb0\u5f55\u3002\u8be5\u8868\u5c06\u5305\u542b\u56db\u5217\uff1a<\/p>\n
\n- saleID\uff1a\u4e0e productID \u548c empID \u5217\u7c7b\u4f3c\uff0c\u6b64\u5217\u5305\u542b\u6bcf\u7b14\u9500\u552e\u7684\u552f\u4e00\u6807\u8bc6\u53f7\uff0c\u6570\u636e\u7c7b\u578b\u4e3a int\u3002\u6b64\u5217\u8fd8\u5177\u6709 UNIQUE \u7ea6\u675f\uff0c\u56e0\u6b64\u53ef\u4ee5\u7528\u4f5c\u9500\u552e\u8868\u7684\u4e3b\u952e\u3002<\/li>\n
- \u6570\u91cf\uff1a\u6bcf\u79cd\u4ea7\u54c1\u7684\u9500\u552e\u5355\u4f4d\u6570\u91cf\u7528 int \u6570\u636e\u7c7b\u578b\u8868\u793a\u3002<\/li>\n
- \u4ea7\u54c1 ID\uff1a\u6240\u552e\u4ea7\u54c1\u7684\u8bc6\u522b\u53f7\u7801\uff0c\u4ee5\u6574\u6570\u8868\u793a\u3002<\/li>\n
- \u9500\u552e\u4eba\u5458\uff1a\u5b8c\u6210\u9500\u552e\u7684\u5458\u5de5\u7684\u8eab\u4efd\u8bc1\u53f7\u7801\u3002<\/li>\n<\/ul>\n
\u4e0e\u56e2\u961f\u8868\u4e2d\u7684 productSpecialty \u5217\u4e00\u6837\uff0c\u60a8\u51b3\u5b9a\u5bf9 productID \u548c salesperson \u5217\u5e94\u7528\u5916\u952e\u7ea6\u675f\u3002\u8fd9\u786e\u4fdd\u8fd9\u4e9b\u5217\u4ec5\u5305\u542b\u4ea7\u54c1\u8868\u4e2d productID \u5217\u548c\u56e2\u961f\u8868\u4e2d empID \u5217\u4e2d\u5206\u522b\u5b58\u5728\u7684\u503c\u3002.<\/p>\n
\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a\u201c\u9500\u552e\u201d\u7684\u8868\u683c\uff0c\u5305\u542b\u4ee5\u4e0b\u56db\u5217\uff1a<\/p>\n
\nCREATE TABLE sales (\r\nsaleID int UNIQUE,\r\nquantity int,\r\nproductID int,\r\nsalesperson int,\r\nPRIMARY KEY (saleID),\r\nFOREIGN KEY (productID) REFERENCES products (productID),\r\nFOREIGN KEY (salesperson) REFERENCES team (empID)\r\n);<\/code><\/pre>\n<\/div>\n\u7136\u540e\uff0c\u901a\u8fc7\u6267\u884c\u4ee5\u4e0b INSERT INTO \u64cd\u4f5c\uff0c\u5c06\u793a\u4f8b\u6570\u636e\u52a0\u8f7d\u5230 Products \u8868\u4e2d\uff1a<\/p>\n
\nINSERT INTO products\r\nVALUES\r\n(1, 'widget', 18.99),\r\n(2, 'gizmo', 14.49),\r\n(3, 'thingamajig', 39.99),\r\n(4, 'doodad', 11.50),\r\n(5, 'whatzit', 29.99);<\/code><\/pre>\n<\/div>\n\u7136\u540e\u5411\u56e2\u961f\u8868\u4e2d\u52a0\u8f7d\u793a\u4f8b\u6570\u636e\uff1a<\/p>\n
\nINSERT INTO team\r\nVALUES\r\n(1, 'Florence', 1),\r\n(2, 'Mary', 4),\r\n(3, 'Diana', 3),\r\n(4, 'Betty', 2);<\/code><\/pre>\n<\/div>\n\u540c\u65f6\uff0c\u5c06\u9500\u552e\u8868\u52a0\u8f7d\u793a\u4f8b\u6570\u636e\uff1a<\/p>\n
\nINSERT INTO sales\r\nVALUES\r\n(1, 7, 1, 1),\r\n(2, 10, 5, 4),\r\n(3, 8, 2, 4),\r\n(4, 1, 3, 3),\r\n(5, 5, 1, 3);<\/code><\/pre>\n<\/div>\n\u6700\u540e\uff0c\u5047\u8bbe\u4f60\u7684\u516c\u53f8\u5728\u9500\u552e\u56e2\u961f\u65e0\u4eba\u53c2\u4e0e\u7684\u60c5\u51b5\u4e0b\u5b8c\u6210\u4e86\u51e0\u7b14\u9500\u552e\u3002\u4e3a\u4e86\u8bb0\u5f55\u8fd9\u4e9b\u9500\u552e\uff0c\u8bf7\u8fd0\u884c\u4ee5\u4e0b\u64cd\u4f5c\uff0c\u5411 Sales \u8868\u4e2d\u6dfb\u52a0\u4e09\u884c\u201c\u9500\u552e\u4eba\u5458\u201d\u5217\u4e3a\u7a7a\u7684\u8bb0\u5f55\uff1a<\/p>\n
\nINSERT INTO sales (saleID, quantity, productID)\r\nVALUES\r\n(6, 1, 5),\r\n(7, 3, 1),\r\n(8, 4, 5);<\/code><\/pre>\n<\/div>\n\u5b8c\u6210\u4e0a\u8ff0\u6b65\u9aa4\u540e\uff0c\u60a8\u5c31\u53ef\u4ee5\u7ee7\u7eed\u9605\u8bfb\u672c\u6307\u5357\u7684\u5176\u4f59\u90e8\u5206\uff0c\u5f00\u59cb\u5b66\u4e60\u5982\u4f55\u5728 SQL \u4e2d\u8fde\u63a5\u8868\u3002.<\/p>\n
\u7406\u89e3 JOIN \u64cd\u4f5c\u7684\u8bed\u6cd5<\/h5>\n
JOIN \u5b50\u53e5\u53ef\u7528\u4e8e\u5404\u79cd SQL \u8bed\u53e5\uff0c\u5305\u62ec UPDATE \u548c DELETE \u64cd\u4f5c\u3002\u4f46\u662f\uff0c\u4e3a\u4e86\u4fbf\u4e8e\u8bf4\u660e\uff0c\u672c\u6307\u5357\u4e2d\u7684\u793a\u4f8b\u4f7f\u7528 SELECT \u67e5\u8be2\u6765\u6f14\u793a JOIN \u5b50\u53e5\u7684\u5de5\u4f5c\u539f\u7406\u3002.<\/p>\n
\u4ee5\u4e0b\u793a\u4f8b\u5c55\u793a\u4e86\u5305\u542b JOIN \u5b50\u53e5\u7684 SELECT \u8bed\u53e5\u7684\u4e00\u822c\u8bed\u6cd5\uff1a<\/p>\n
\nSELECT table1.column1, table2.column2\r\nFROM table1 JOIN table2\r\nON search_condition;<\/code><\/pre>\n<\/div>\n\u6b64\u8bed\u6cd5\u4ee5 SELECT \u8bed\u53e5\u5f00\u5934\uff0c\u8be5\u8bed\u53e5\u4ece\u4e24\u4e2a\u4e0d\u540c\u7684\u8868\u4e2d\u8fd4\u56de\u4e24\u5217\u6570\u636e\u3002\u8bf7\u6ce8\u610f\uff0c\u7531\u4e8e JOIN \u5b50\u53e5\u4f1a\u6bd4\u8f83\u591a\u4e2a\u8868\u7684\u5185\u5bb9\uff0c\u56e0\u6b64\u6b64\u793a\u4f8b\u8bed\u6cd5\u9700\u8981\u6307\u5b9a\u6bcf\u4e00\u5217\u8981\u4ece\u54ea\u4e2a\u8868\u4e2d\u9009\u62e9\uff0c\u5373\u5728\u5217\u540d\u524d\u52a0\u4e0a\u8868\u540d\u548c\u4e00\u4e2a\u53e5\u70b9\u3002\u8fd9\u79f0\u4e3a\u5b8c\u5168\u9650\u5b9a\u5217\u5f15\u7528\u3002.<\/p>\n
\u4f60\u53ef\u4ee5\u5728\u4efb\u4f55\u64cd\u4f5c\u4e2d\u4f7f\u7528\u5b8c\u5168\u9650\u5b9a\u7684\u5217\u5f15\u7528\uff0c\u4f46\u4e25\u683c\u6765\u8bf4\uff0c\u53ea\u6709\u5f53\u4e24\u4e2a\u6765\u81ea\u4e0d\u540c\u8868\u7684\u5217\u540c\u540d\u65f6\u624d\u9700\u8981\u8fd9\u6837\u505a\u3002\u4e0d\u8fc7\uff0c\u5728\u5904\u7406\u591a\u4e2a\u8868\u65f6\uff0c\u4f7f\u7528\u5b8c\u5168\u9650\u5b9a\u7684\u5217\u5f15\u7528\u662f\u4e00\u79cd\u826f\u597d\u7684\u5b9e\u8df5\uff0c\u56e0\u4e3a\u5b83\u4eec\u6709\u52a9\u4e8e\u63d0\u9ad8 JOIN \u64cd\u4f5c\u7684\u53ef\u8bfb\u6027\u548c\u6613\u61c2\u6027\u3002.<\/p>\n
SELECT \u8bed\u53e5\u4e4b\u540e\u662f FROM \u5b50\u53e5\u3002\u5728\u4efb\u4f55\u67e5\u8be2\u4e2d\uff0cFROM \u5b50\u53e5\u7528\u4e8e\u5b9a\u4e49\u9700\u8981\u641c\u7d22\u7684\u6570\u636e\u96c6\uff0c\u4ee5\u4fbf\u8fd4\u56de\u6240\u9700\u6570\u636e\u3002\u552f\u4e00\u7684\u533a\u522b\u5728\u4e8e\uff0cFROM \u5b50\u53e5\u5305\u542b\u4e24\u4e2a\u7531 JOIN \u5173\u952e\u5b57\u8fde\u63a5\u7684\u8868\u3002\u7f16\u5199\u67e5\u8be2\u7684\u4e00\u4e2a\u6709\u6548\u65b9\u6cd5\u662f\u8bb0\u4f4f\u9009\u62e9\u8981\u67e5\u8be2\u7684\u8868\u4e2d\u7684\u5217\u3002.<\/p>\n
\u7136\u540e\uff0c\u8fd8\u6709\u4e00\u4e2a ON \u5b50\u53e5\uff0c\u5b83\u901a\u8fc7\u5b9a\u4e49\u641c\u7d22\u6761\u4ef6\u6765\u89e3\u91ca\u67e5\u8be2\u5982\u4f55\u8fde\u63a5\u4e24\u4e2a\u8868\u3002\u641c\u7d22\u6761\u4ef6\u662f\u4e00\u7ec4\u4e00\u4e2a\u6216\u591a\u4e2a\u8bed\u53e5\u6216\u8868\u8fbe\u5f0f\uff0c\u5bf9\u4e8e\u7279\u5b9a\u6761\u4ef6\uff0c\u8fd9\u4e9b\u8bed\u53e5\u6216\u8868\u8fbe\u5f0f\u7684\u8ba1\u7b97\u7ed3\u679c\u53ef\u80fd\u4e3a\u00ab\u771f\u00bb\u3001\u00ab\u5047\u00bb\u6216\u00ab\u672a\u77e5\u00bb\u3002\u53ef\u4ee5\u5c06 JOIN \u64cd\u4f5c\u7406\u89e3\u4e3a\u5c06\u4e24\u4e2a\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\u5408\u5e76\uff0c\u7136\u540e\u8fd4\u56de ON \u5b50\u53e5\u4e2d\u641c\u7d22\u6761\u4ef6\u8ba1\u7b97\u7ed3\u679c\u4e3a\u201c\u771f\u201d\u7684\u6bcf\u4e00\u884c\u3002.<\/p>\n
\u5728 ON \u5b50\u53e5\u4e2d\uff0c\u901a\u5e38\u6709\u5fc5\u8981\u5305\u542b\u4e00\u4e2a\u641c\u7d22\u6761\u4ef6\uff0c\u7528\u4e8e\u6d4b\u8bd5\u4e24\u4e2a\u76f8\u5173\u5217\uff08\u4f8b\u5982\uff0c\u4e00\u4e2a\u8868\u7684\u5916\u952e\u548c\u8be5\u5916\u952e\u5f15\u7528\u7684\u53e6\u4e00\u4e2a\u8868\u7684\u4e3b\u952e\uff09\u7684\u503c\u662f\u5426\u76f8\u7b49\u3002\u8fd9\u6709\u65f6\u88ab\u79f0\u4e3a\u7b49\u503c\u8fde\u63a5\u3002.<\/p>\n
\u4e3a\u4e86\u6f14\u793a equi \u5982\u4f55\u8fde\u63a5\u6765\u81ea\u591a\u4e2a\u8868\u7684\u5339\u914d\u6570\u636e\uff0c\u8bf7\u4f7f\u7528\u60a8\u4e4b\u524d\u6dfb\u52a0\u7684\u793a\u4f8b\u6570\u636e\u8fd0\u884c\u4ee5\u4e0b\u67e5\u8be2\u3002\u6b64\u67e5\u8be2\u5c06 Products \u8868\u548c Team \u8868\u8fde\u63a5\u8d77\u6765\uff0c\u5e76\u4f7f\u7528\u641c\u7d22\u6761\u4ef6\u6d4b\u8bd5\u5b83\u4eec\u5404\u81ea\u7684 productID \u548c productSpecialty \u5217\u4e2d\u7684\u503c\u662f\u5426\u5339\u914d\u3002\u7136\u540e\uff0c\u5b83\u4f1a\u8fd4\u56de\u6bcf\u4e2a\u9500\u552e\u56e2\u961f\u6210\u5458\u7684\u59d3\u540d\u3001\u4ed6\u4eec\u8d1f\u8d23\u7684\u6bcf\u4e2a\u4ea7\u54c1\u7684\u540d\u79f0\u4ee5\u53ca\u8fd9\u4e9b\u4ea7\u54c1\u7684\u4ef7\u683c\uff1a<\/p>\n
\n\nSELECT team.empName, products.productName, products.price\r\nFROM products JOIN team\r\nON products.productID = team.productSpecialty<\/code><\/pre>\n<\/div>\n\u062f\u0631 \u0627\u06cc\u0646\u062c\u0627 \u0645\u062c\u0645\u0648\u0639\u0647 \u0646\u062a\u0627\u06cc\u062c \u0627\u06cc\u0646 \u067e\u0631\u0633 \u0648 \u062c\u0648 \u0627\u0633\u062a:<\/p>\n<\/div>\n
\n\nOutput\r\n+----------+-------------+-------+\r\n| empName | productName | price |\r\n+----------+-------------+-------+\r\n| Florence | widget | 18.99 |\r\n| Mary | doodad | 11.50 |\r\n| Diana | thingamajig | 39.99 |\r\n| Betty | gizmo | 14.49 |\r\n+----------+-------------+-------+\r\n4 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u4e3a\u4e86\u8bf4\u660e SQL \u5982\u4f55\u5c06\u8fd9\u4e9b\u8868\u7ec4\u5408\u8d77\u6765\u5f62\u6210\u8fd9\u4e2a\u7ed3\u679c\u96c6\uff0c\u6211\u4eec\u6765\u4ed4\u7ec6\u770b\u770b\u8fd9\u4e2a\u8fc7\u7a0b\u3002\u9700\u8981\u8bf4\u660e\u7684\u662f\uff0c\u4ee5\u4e0b\u5e76\u975e\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf\u8fde\u63a5\u4e24\u4e2a\u8868\u7684\u5b9e\u9645\u65b9\u5f0f\uff0c\u4f46\u5c06 JOIN \u64cd\u4f5c\u89c6\u4e3a\u4e00\u4e2a\u8fc7\u7a0b\u4f1a\u5f88\u6709\u5e2e\u52a9\u3002.<\/p>\n
\u9996\u5148\uff0c\u8be5\u67e5\u8be2\u4f1a\u6253\u5370\u51fa FROM \u5b50\u53e5\u4e2d\u7b2c\u4e00\u4e2a\u8868\u4e2d\u6bcf\u4e00\u884c\u548c\u6bcf\u4e00\u5217\u7684\u4ea7\u54c1\uff1a<\/p>\n
\nJOIN Process Example\r\n+-----------+-------------+-------+\r\n| productID | productName | price |\r\n+-----------+-------------+-------+\r\n| 1 | widget | 18.99 |\r\n| 2 | gizmo | 14.49 |\r\n| 3 | thingamajig | 39.99 |\r\n| 4 | doodad | 11.50 |\r\n| 5 | whatzit | 29.99 |\r\n+-----------+-------------+-------+<\/code><\/pre>\n\u0633\u067e\u0633\u060c \u0628\u0647 \u0647\u0631 \u06cc\u06a9 \u0627\u0632 \u0627\u06cc\u0646 \u0631\u062f\u06cc\u0641\u200c\u0647\u0627 \u0646\u06af\u0627\u0647 \u0645\u06cc\u200c\u06a9\u0646\u062f \u0648 \u0628\u0627 \u0647\u0631 \u0631\u062f\u06cc\u0641\u06cc \u0627\u0632 \u062c\u062f\u0648\u0644 \u062a\u06cc\u0645 \u06a9\u0647 productSpecialty \u0622\u0646 \u0628\u0631\u0627\u0628\u0631 \u0628\u0627 \u0645\u0642\u062f\u0627\u0631 productID \u062f\u0631 \u0622\u0646 \u0633\u0637\u0631 \u0627\u0633\u062a\u060c \u0645\u0637\u0627\u0628\u0642\u062a \u0645\u06cc\u200c\u062f\u0647\u062f:<\/div>\n\n\nJOIN Process Example\r\n+-----------+-------------+-------+-------+----------+------------------+\r\n| productID | productName | price | empID | empName | productSpecialty |\r\n+-----------+-------------+-------+-------+----------+------------------+\r\n| 1 | widget | 18.99 | 1 | Florence | 1 |\r\n| 2 | gizmo | 14.49 | 4 | Betty | 2 |\r\n| 3 | thingamajig | 39.99 | 3 | Diana | 3 |\r\n| 4 | doodad | 11.50 | 2 | Mary | 4 |\r\n| 5 | whatzit | 29.99 | | | |\r\n+-----------+-------------+-------+-------+----------+------------------+<\/code><\/pre>\n\u0633\u067e\u0633\u060c \u0633\u0637\u0631\u0647\u0627\u06cc\u06cc \u0631\u0627 \u06a9\u0647 \u0645\u0637\u0627\u0628\u0642\u062a \u0646\u062f\u0627\u0631\u0646\u062f \u0631\u0627 \u0628\u0631\u0634 \u0645\u06cc\u200c\u062f\u0647\u062f \u0648 \u0633\u062a\u0648\u0646\u200c\u0647\u0627 \u0631\u0627 \u0628\u0631 \u0627\u0633\u0627\u0633 \u062a\u0631\u062a\u06cc\u0628 \u0622\u0646\u0647\u0627 \u062f\u0631 \u0639\u0628\u0627\u0631\u062a SELECT \u0645\u0631\u062a\u0628 \u0645\u06cc\u200c\u06a9\u0646\u062f\u060c \u0633\u062a\u0648\u0646\u200c\u0647\u0627\u06cc\u06cc \u0631\u0627 \u06a9\u0647 \u0645\u0634\u062e\u0635 \u0646\u0634\u062f\u0647 \u0628\u0648\u062f\u0646\u062f \u062d\u0630\u0641 \u0645\u06cc\u200c\u06a9\u0646\u062f\u060c \u0631\u062f\u06cc\u0641\u200c\u0647\u0627 \u0631\u0627 \u0645\u062a\u0648\u0633\u0644 \u0645\u06cc\u200c\u06a9\u0646\u062f \u0648 \u0645\u062c\u0645\u0648\u0639\u0647 \u0646\u062a\u0627\u06cc\u062c \u0646\u0647\u0627\u06cc\u06cc \u0631\u0627 \u0628\u0631\u0645\u06cc\u200c\u06af\u0631\u062f\u0627\u0646\u062f:<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\nJOIN Process Example\r\n+----------+-------------+-------+\r\n| empName | productName | price |\r\n+----------+-------------+-------+\r\n| Florence | widget | 18.99 |\r\n| Mary | doodad | 11.50 |\r\n| Diana | thingamajig | 39.99 |\r\n| Betty | gizmo | 14.49 |\r\n+----------+-------------+-------+\r\n4 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u4f7f\u7528\u7b49\u503c\u8fde\u63a5\u662f\u8fde\u63a5\u8868\u6700\u5e38\u7528\u7684\u65b9\u6cd5\uff0c\u4f46\u5176\u4ed6 SQL \u8fd0\u7b97\u7b26\uff0c\u4f8b\u5982 <\u3001>\u3001LIKE\u3001NOT LIKE \u751a\u81f3 BETWEEN\uff0c\u4e5f\u53ef\u4ee5\u7528\u4e8e ON \u5b50\u53e5\u7684\u641c\u7d22\u6761\u4ef6\u3002\u7136\u800c\uff0c\u8bf7\u6ce8\u610f\uff0c\u4f7f\u7528\u66f4\u590d\u6742\u7684\u641c\u7d22\u6761\u4ef6\u53ef\u80fd\u4f1a\u4f7f\u9884\u6d4b\u7ed3\u679c\u96c6\u4e2d\u4f1a\u51fa\u73b0\u54ea\u4e9b\u6570\u636e\u53d8\u5f97\u56f0\u96be\u3002.<\/p>\n
\u5728\u5927\u591a\u6570\u5b9e\u73b0\u4e2d\uff0c\u60a8\u53ef\u4ee5\u6839\u636e\u4efb\u4f55\u5177\u6709 SQL \u6807\u51c6\u6240\u79f0\u7684\u00ab\u9650\u5b9a\u8fde\u63a5\u00bb\uff08qualified JOIN\uff09\u6570\u636e\u7c7b\u578b\u7684\u5217\u96c6\u6765\u8fde\u63a5\u8868\u3002\u8fd9\u610f\u5473\u7740\uff0c\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u60a8\u53ef\u4ee5\u5c06\u5305\u542b\u6570\u503c\u6570\u636e\u7684\u5217\u8fde\u63a5\u5230\u4efb\u4f55\u5176\u4ed6\u5305\u542b\u6570\u503c\u6570\u636e\u7684\u5217\uff0c\u800c\u65e0\u9700\u8003\u8651\u5bf9\u5e94\u7684\u6570\u636e\u7c7b\u578b\u3002\u7c7b\u4f3c\u5730\uff0c\u60a8\u901a\u5e38\u53ef\u4ee5\u5c06\u5305\u542b\u5b57\u7b26\u503c\u7684\u5217\u8fde\u63a5\u5230\u4efb\u4f55\u5176\u4ed6\u5305\u542b\u5b57\u7b26\u6570\u636e\u7684\u5217\u3002\u5982\u524d\u6240\u8ff0\uff0c\u7528\u4e8e\u8fde\u63a5\u4e24\u4e2a\u8868\u7684\u5217\u901a\u5e38\u662f\u8868\u793a\u8868\u4e4b\u95f4\u5173\u7cfb\u7684\u5217\uff0c\u4f8b\u5982\u5916\u952e\u548c\u5b83\u6240\u5f15\u7528\u7684\u53e6\u4e00\u4e2a\u8868\u7684\u4e3b\u952e\u3002.<\/p>\n
\u8bb8\u591a SQL \u5b9e\u73b0\u5141\u8bb8\u4f7f\u7528 USING \u5173\u952e\u5b57\u800c\u4e0d\u662f ON \u6765\u8fde\u63a5\u540c\u540d\u5217\u3002\u6b64\u7c7b\u64cd\u4f5c\u7684\u8bed\u6cd5\u53ef\u80fd\u5982\u4e0b\uff1a<\/p>\n
\nSELECT table1.column1, table2.column2\r\nFROM table1 JOIN table2\r\nUSING (related_column);<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u5728\u8fd9\u4e2a\u793a\u4f8b\u8bed\u6cd5\u4e2d\uff0cUSING \u8bed\u53e5\u7b49\u4ef7\u4e8e ON table1.related_column = table2.related_column;.<\/p>\n
\u7531\u4e8e\u9500\u552e\u548c\u4ea7\u54c1\u8868\u5404\u6709\u4e00\u4e2a\u540d\u4e3a productID \u7684\u5217\uff0c\u60a8\u53ef\u4ee5\u4f7f\u7528 USING \u5173\u952e\u5b57\u5c06\u8fd9\u4e24\u5217\u8fde\u63a5\u8d77\u6765\u3002\u4ee5\u4e0b\u8bed\u53e5\u6267\u884c\u6b64\u64cd\u4f5c\uff0c\u5e76\u8fd4\u56de\u6bcf\u7b14\u9500\u552e\u7684 saleID\u3001\u9500\u552e\u6570\u91cf\u3001\u6bcf\u4ef6\u552e\u51fa\u4ea7\u54c1\u7684\u540d\u79f0\u53ca\u5176\u4ef7\u683c\u3002\u5b83\u8fd8\u4f1a\u6309 saleID \u503c\u5347\u5e8f\u5bf9\u7ed3\u679c\u96c6\u8fdb\u884c\u6392\u5e8f\uff1a<\/p>\n
\nSELECT sales.saleID, sales.quantity, products.productName, products.price\r\nFROM sales JOIN products\r\nUSING (productID)\r\nORDER BY saleID;<\/code><\/pre>\n<\/div>\n<\/div>\n\n\nOutput\r\n+--------+----------+-------------+-------+\r\n| saleID | quantity | productName | price |\r\n+--------+----------+-------------+-------+\r\n| 1 | 7 | widget | 18.99 |\r\n| 2 | 10 | whatzit | 29.99 |\r\n| 3 | 8 | gizmo | 14.49 |\r\n| 4 | 1 | thingamajig | 39.99 |\r\n| 5 | 5 | widget | 18.99 |\r\n| 6 | 1 | whatzit | 29.99 |\r\n| 7 | 3 | widget | 18.99 |\r\n| 8 | 4 | whatzit | 29.99 |\r\n+--------+----------+-------------+-------+\r\n8 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u5728\u8fde\u63a5\u8868\u65f6\uff0c\u6570\u636e\u5e93\u7cfb\u7edf\u6709\u65f6\u4f1a\u4ee5\u96be\u4ee5\u9884\u6d4b\u7684\u65b9\u5f0f\u6392\u5217\u884c\u3002\u6dfb\u52a0\u7c7b\u4f3c\u8fd9\u6837\u7684 ORDER BY \u5b50\u53e5\u53ef\u4ee5\u5e2e\u52a9\u4f7f\u7ed3\u679c\u96c6\u66f4\u6e05\u6670\u6613\u8bfb\u3002.<\/p>\n
\u5408\u5e76\u4e24\u4e2a\u4ee5\u4e0a\u7684\u8868<\/h5>\n
\u6709\u65f6\u60a8\u53ef\u80fd\u9700\u8981\u5408\u5e76\u6765\u81ea\u4e24\u4e2a\u4ee5\u4e0a\u8868\u7684\u6570\u636e\u3002\u60a8\u53ef\u4ee5\u901a\u8fc7\u5728\u5176\u4ed6 JOIN \u5b50\u53e5\u4e2d\u5d4c\u5957 JOIN \u5b50\u53e5\u6765\u8fde\u63a5\u4efb\u610f\u6570\u91cf\u7684\u8868\u3002\u4ee5\u4e0b\u8bed\u6cd5\u793a\u4f8b\u5c55\u793a\u4e86\u8fde\u63a5\u4e09\u4e2a\u8868\u7684\u60c5\u51b5\uff1a<\/p>\n
\nSELECT table1.column1, table2.column2, table3.column3\r\nFROM table1 JOIN table2\r\nON table1.related_column = table2.related_column\r\nJOIN table3\r\nON table3.related_column = table1_or_2.related_column;<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u6b64\u793a\u4f8b\u8bed\u53e5\u4e2d\u7684 FROM \u5b50\u53e5\u9996\u5148\u5c06\u8868 1 \u8fde\u63a5\u5230\u8868 2\u3002\u5728\u6b64 ON \u5b50\u53e5\u4e4b\u540e\uff0c\u5b83\u5f00\u59cb\u7b2c\u4e8c\u4e2a JOIN\uff0c\u5c06\u6700\u521d\u8fde\u63a5\u7684\u8868\u96c6\u4e0e\u8868 3 \u5408\u5e76\u3002\u8bf7\u6ce8\u610f\uff0c\u7b2c\u4e09\u4e2a\u8868\u53ef\u4ee5\u8fde\u63a5\u5230\u7b2c\u4e00\u4e2a\u8868\u6216\u7b2c\u4e8c\u4e2a\u8868\u4e2d\u7684\u5217\u3002.<\/p>\n
\u4f8b\u5982\uff0c\u5047\u8bbe\u4f60\u60f3\u77e5\u9053\u4f60\u7684\u5458\u5de5\u521b\u9020\u4e86\u591a\u5c11\u9500\u552e\u989d\uff0c\u4f46\u4f60\u53ea\u5173\u5fc3\u5305\u542b\u8be5\u5458\u5de5\u64c5\u957f\u7684\u4ea7\u54c1\u7684\u9500\u552e\u8bb0\u5f55\u3002.<\/p>\n
\u8981\u83b7\u53d6\u6b64\u4fe1\u606f\uff0c\u60a8\u53ef\u4ee5\u8fd0\u884c\u4ee5\u4e0b\u67e5\u8be2\u3002\u6b64\u67e5\u8be2\u9996\u5148\u5c06 Products \u8868\u548c Sales \u8868\u901a\u8fc7\u5339\u914d\u5404\u81ea\u7684 productID \u5217\u8fde\u63a5\u8d77\u6765\u3002\u7136\u540e\uff0c\u5b83\u5c06 Team \u8868\u4e0e\u524d\u4e24\u4e2a\u8868\u8fde\u63a5\u8d77\u6765\uff0c\u65b9\u6cd5\u662f\u5c06\u521d\u59cb JOIN \u8fde\u63a5\u4e2d\u7684\u6bcf\u4e00\u884c\u4e0e\u5176 productSpecialty \u5217\u5339\u914d\u3002\u63a5\u4e0b\u6765\uff0c\u67e5\u8be2\u4f7f\u7528 WHERE \u5b50\u53e5\u7b5b\u9009\u7ed3\u679c\uff0c\u4ec5\u8fd4\u56de\u5339\u914d\u7684\u5458\u5de5\u4e5f\u662f\u5b8c\u6210\u9500\u552e\u7684\u4eba\u5458\u7684\u884c\u3002\u67e5\u8be2\u8fd8\u5305\u542b\u4e00\u4e2a ORDER BY \u5b50\u53e5\uff0c\u8be5\u5b50\u53e5\u6309 saleID \u5217\u7684\u503c\u5347\u5e8f\u5bf9\u6700\u7ec8\u7ed3\u679c\u8fdb\u884c\u6392\u5e8f\uff1a<\/p>\n
\nSELECT sales.saleID,\r\nteam.empName,\r\nproducts.productName,\r\n(sales.quantity * products.price)\r\nFROM products JOIN sales\r\nUSING (productID)\r\nJOIN team\r\nON team.productSpecialty = sales.productID\r\nWHERE team.empID = sales.salesperson\r\nORDER BY sales.saleID;\r\n<\/code><\/pre>\n<\/div>\n<\/div>\n\u8bf7\u6ce8\u610f\uff0cSELECT \u8bed\u53e5\u5217\u51fa\u7684\u5217\u4e2d\u5305\u542b\u4e00\u6761\u8bed\u53e5\uff0c\u8be5\u8bed\u53e5\u5c06 Sales \u8868\u4e2d Value \u5217\u7684\u503c\u4e58\u4ee5 Products \u8868\u4e2d Price \u5217\u7684\u503c\u3002Products \u8868\u4f1a\u5728\u5339\u914d\u7684\u884c\u4e2d\u8fd4\u56de\u8fd9\u4e9b\u503c\uff1a<\/div>\n\n\nOutput\r\n+--------+----------+-------------+-----------------------------------+\r\n| saleID | empName | productName | (sales.quantity * products.price) |\r\n+--------+----------+-------------+-----------------------------------+\r\n| 1 | Florence | widget | 132.93 |\r\n| 3 | Betty | gizmo | 115.92 |\r\n| 4 | Diana | thingamajig | 39.99 |\r\n+--------+----------+-------------+-----------------------------------+\r\n3 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\u6240\u6709\u793a\u4f8b\u90fd\u53ea\u4f7f\u7528\u4e86\u4e00\u79cd\u7c7b\u578b\u7684 JOIN \u8868\u8fbe\u5f0f\uff1a\u5185\u8fde\u63a5\u3002\u8bf7\u7ee7\u7eed\u9605\u8bfb\u4e0b\u4e00\u8282\uff0c\u4e86\u89e3\u5185\u8fde\u63a5\u3001\u5916\u8fde\u63a5\u53ca\u5176\u533a\u522b\u7684\u6982\u8ff0\u3002.<\/p>\n
\u5185\u8fde\u63a5\u4e0e\u5916\u8fde\u63a5\u64cd\u4f5c<\/h2>\n
JOIN \u8bed\u53e5\u4e3b\u8981\u6709\u4e24\u79cd\u7c7b\u578b\uff1a\u5185\u8fde\u63a5\u548c\u5916\u8fde\u63a5\u3002\u8fd9\u4e24\u79cd\u8fde\u63a5\u7684\u533a\u522b\u5728\u4e8e\u5b83\u4eec\u8fd4\u56de\u7684\u6570\u636e\u3002\u5185\u8fde\u63a5\u53ea\u8fd4\u56de\u6765\u81ea\u6bcf\u4e2a\u8fde\u63a5\u8868\u7684\u5339\u914d\u884c\uff0c\u800c\u5916\u8fde\u63a5\u5219\u8fd4\u56de\u5339\u914d\u884c\u548c\u4e0d\u5339\u914d\u884c\u3002.<\/p>\n
\u524d\u9762\u51e0\u8282\u7684\u8bed\u6cd5\u548c\u793a\u4f8b\u67e5\u8be2\u90fd\u4f7f\u7528\u4e86 INNER JOIN \u8bed\u53e5\uff0c\u5373\u4f7f\u5b83\u4eec\u90fd\u6ca1\u6709\u5305\u542b INNER \u5173\u952e\u5b57\u3002\u5927\u591a\u6570 SQL \u5b9e\u73b0\u4f1a\u5c06\u6240\u6709 JOIN \u8bed\u53e5\u90fd\u89c6\u4e3a INNER JOIN\uff0c\u9664\u975e\u53e6\u6709\u660e\u786e\u8bf4\u660e\u3002.<\/p>\n
\u6307\u5b9a\u5916\u90e8 JOIN \u7684\u67e5\u8be2\u4f1a\u5c06\u591a\u4e2a\u8868\u8fde\u63a5\u8d77\u6765\uff0c\u5e76\u8fd4\u56de\u6240\u6709\u5339\u914d\u7684\u884c\u4ee5\u53ca\u6240\u6709\u4e0d\u5339\u914d\u7684\u884c\u3002\u8fd9\u5bf9\u4e8e\u67e5\u627e\u5305\u542b\u7f3a\u5931\u503c\u7684\u884c\u6216\u53ef\u4ee5\u63a5\u53d7\u90e8\u5206\u5339\u914d\u7684\u60c5\u51b5\u975e\u5e38\u6709\u7528\u3002.<\/p>\n
\u5916\u8fde\u63a5\u64cd\u4f5c\u53ef\u4ee5\u5206\u4e3a\u4e09\u79cd\u7c7b\u578b\uff1a\u5de6\u5916\u8fde\u63a5\u3001\u53f3\u5916\u8fde\u63a5\u548c\u5168\u5916\u8fde\u63a5\u3002\u5de6\u5916\u8fde\u63a5\uff08\u7b80\u79f0\u5de6\u8fde\u63a5\uff09\u8fd4\u56de\u4e24\u4e2a\u8fde\u63a5\u8868\u4e2d\u6240\u6709\u5339\u914d\u7684\u884c\uff0c\u4ee5\u53ca\u201c\u5de6\u201d\u8868\u4e2d\u6240\u6709\u4e0d\u5339\u914d\u7684\u884c\u3002\u5728 JOIN \u64cd\u4f5c\u7684\u4e0a\u4e0b\u6587\u4e2d\uff0c\u201c\u5de6\u201d\u8868\u59cb\u7ec8\u662f\u7d27\u8ddf\u5728 FROM \u5173\u952e\u5b57\u4e4b\u540e\u3001JOIN \u5173\u952e\u5b57\u5de6\u4fa7\u7684\u7b2c\u4e00\u4e2a\u8868\u3002\u7c7b\u4f3c\u5730\uff0c\u00ab\u53f3\u00bb\u8868\u662f\u7b2c\u4e8c\u4e2a\u8868\uff0c\u5373\u7d27\u8ddf\u5728 JOIN \u4e4b\u540e\u7684\u8868\u3002\u53f3\u5916\u8fde\u63a5\u8fd4\u56de\u4e24\u4e2a\u8fde\u63a5\u8868\u4e2d\u6240\u6709\u5339\u914d\u7684\u884c\uff0c\u4ee5\u53ca\u00ab\u53f3\u00bb\u8868\u4e2d\u6240\u6709\u4e0d\u5339\u914d\u7684\u884c\u3002\u5168\u5916\u8fde\u63a5\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u7684\u6240\u6709\u884c\uff0c\u5305\u62ec\u4efb\u4e00\u8868\u4e2d\u4e0d\u5339\u914d\u7684\u884c\u3002.<\/p>\n
\u4e3a\u4e86\u6f14\u793a\u8fd9\u4e9b\u4e0d\u540c\u7c7b\u578b\u7684 JOIN \u5b50\u53e5\u5982\u4f55\u8fd4\u56de\u6570\u636e\uff0c\u8bf7\u5728\u4e0a\u4e00\u8282\u201c\u8fde\u63a5\u548c\u8bbe\u7f6e\u793a\u4f8b\u6570\u636e\u5e93\u201d\u4e2d\u521b\u5efa\u7684\u8868\u4e0a\u8fd0\u884c\u4ee5\u4e0b\u793a\u4f8b\u67e5\u8be2\u3002\u8fd9\u4e9b\u67e5\u8be2\u5b8c\u5168\u76f8\u540c\uff0c\u53ea\u662f\u6bcf\u4e2a\u67e5\u8be2\u6307\u5b9a\u4e86\u4e0d\u540c\u7c7b\u578b\u7684 JOIN \u5b50\u53e5\u3002.<\/p>\n
\u7b2c\u4e00\u4e2a\u4f8b\u5b50\u4f7f\u7528\u5185\u90e8\u8fde\u63a5 (INNER JOIN) \u5c06\u9500\u552e\u8868\u548c\u56e2\u961f\u8868\u901a\u8fc7\u5339\u914d\u76f8\u5e94\u7684\u9500\u552e\u4eba\u5458 (salesperson) \u548c\u5458\u5de5 ID (empID) \u5217\u6765\u5408\u5e76\u3002\u540c\u6837\uff0c\u5373\u4f7f\u6ca1\u6709\u663e\u5f0f\u5305\u542b INNER \u5173\u952e\u5b57\uff0c\u5b83\u4e5f\u9690\u542b\u5728\u5185\uff1a<\/p>\n
\nSELECT sales.saleID, sales.quantity, sales.salesperson, team.empName \r\nFROM sales JOIN team\r\nON sales.salesperson = team.empID;<\/code><\/pre>\n<\/div>\n<\/div>\n\u7531\u4e8e\u6b64\u67e5\u8be2\u4f7f\u7528\u4e86\u5185\u90e8 JOIN \u5b50\u53e5\uff0c\u56e0\u6b64\u5b83\u53ea\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u5339\u914d\u7684\u884c\uff1a<\/div>\n\n\nOutput\r\n+--------+----------+-------------+----------+\r\n| saleID | quantity | salesperson | empName |\r\n+--------+----------+-------------+----------+\r\n| 1 | 7 | 1 | Florence |\r\n| 4 | 1 | 3 | Diana |\r\n| 5 | 5 | 3 | Diana |\r\n| 2 | 10 | 4 | Betty |\r\n| 3 | 8 | 4 | Betty |\r\n+--------+----------+-------------+----------+\r\n5 rows in set (0.00 sec)<\/pre>\n<\/div>\n<\/div>\n\u6b64\u7248\u672c\u7684\u67e5\u8be2\u4f7f\u7528\u4e86 LEFT OUTER JOIN \u5b50\u53e5\uff1a<\/div>\n\n\nSELECT sales.saleID, sales.quantity, sales.salesperson, team.empName\r\nFROM sales LEFT OUTER JOIN team\r\nON sales.salesperson = team.empID;<\/code><\/pre>\n<\/div>\n<\/div>\n\u4e0e\u4e4b\u524d\u7684\u67e5\u8be2\u7c7b\u4f3c\uff0c\u6b64\u67e5\u8be2\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u6240\u6709\u5339\u914d\u7684\u503c\u3002\u4f46\u662f\uff0c\u5b83\u8fd4\u56de\u7684\u662f\u00ab\u5de6\u00bb\u8868\uff08\u5728\u672c\u4f8b\u4e2d\u4e3a Sales \u8868\uff09\u4e2d\u5728\u00ab\u53f3\u00bb\u8868\uff08Team \u8868\uff09\u4e2d\u6ca1\u6709\u5339\u914d\u9879\u7684\u6240\u6709\u503c\u3002\u7531\u4e8e\u5de6\u8868\u4e2d\u7684\u8fd9\u4e9b\u884c\u5728\u53f3\u8868\u4e2d\u6ca1\u6709\u5339\u914d\u9879\uff0c\u56e0\u6b64\u4e0d\u5339\u914d\u7684\u503c\u5c06\u8fd4\u56de NULL\u3002<\/div>\n\n\nOutput\r\n+--------+----------+-------------+----------+\r\n| saleID | quantity | salesperson | empName |\r\n+--------+----------+-------------+----------+\r\n| 1 | 7 | 1 | Florence |\r\n| 2 | 10 | 4 | Betty |\r\n| 3 | 8 | 4 | Betty |\r\n| 4 | 1 | 3 | Diana |\r\n| 5 | 5 | 3 | Diana |\r\n| 6 | 1 | NULL | NULL |\r\n| 7 | 3 | NULL | NULL |\r\n| 8 | 4 | NULL | NULL |\r\n+--------+----------+-------------+----------+\r\n8 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\u4ee5\u4e0b\u7248\u672c\u7684\u67e5\u8be2\u4f7f\u7528\u4e86 RIGHT JOIN \u5b50\u53e5\uff1a<\/div>\n\n\nSELECT sales.saleID, sales.quantity, sales.salesperson, team.empName\r\nFROM sales RIGHT JOIN team\r\nON sales.salesperson = team.empID;<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u8bf7\u6ce8\u610f\uff0c\u6b64\u67e5\u8be2\u7684 JOIN \u5b50\u53e5\u662f RIGHT JOIN \u800c\u4e0d\u662f RIGHT OUTER JOIN\u3002\u6b63\u5982 INNER JOIN \u5b50\u53e5\u4e0d\u9700\u8981\u6307\u5b9a INNER \u5173\u952e\u5b57\u4e00\u6837\uff0c\u5f53\u60a8\u7f16\u5199 LEFT JOIN \u6216 RIGHT JOIN \u65f6\uff0cOUTER \u5173\u952e\u5b57\u662f\u9690\u542b\u7684\u3002.<\/p>\n
\u6b64\u67e5\u8be2\u7684\u7ed3\u679c\u4e0e\u524d\u4e00\u4e2a\u67e5\u8be2\u76f8\u53cd\uff0c\u5b83\u8fd4\u56de\u4e24\u4e2a\u8868\u4e2d\u7684\u6bcf\u4e00\u884c\uff0c\u4f46\u53ea\u8fd4\u56de\u201c\u6b63\u786e\u201d\u8868\u4e2d\u7684\u552f\u4e00\u884c\uff1a<\/p>\n
\nOutput\r\n+--------+----------+-------------+----------+\r\n| saleID | quantity | salesperson | empName |\r\n+--------+----------+-------------+----------+\r\n| 1 | 7 | 1 | Florence |\r\n| NULL | NULL | NULL | Mary |\r\n| 4 | 1 | 3 | Diana |\r\n| 5 | 5 | 3 | Diana |\r\n| 2 | 10 | 4 | Betty |\r\n| 3 | 8 | 4 | Betty |\r\n+--------+----------+-------------+----------+\r\n6 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\nJOIN \u5b50\u53e5\u4e2d\u7684\u8868\u548c\u5217\u522b\u540d<\/p>\n
\u5f53\u8fde\u63a5\u540d\u79f0\u8fc7\u957f\u6216\u63cf\u8ff0\u6027\u5f88\u5f3a\u7684\u8868\u65f6\uff0c\u7f16\u5199\u591a\u4e2a\u5b8c\u6574\u7684\u5217\u5f15\u7528\u4f1a\u53d8\u5f97\u975e\u5e38\u7e41\u7410\u3002\u4e3a\u4e86\u907f\u514d\u8fd9\u79cd\u60c5\u51b5\uff0c\u7528\u6237\u6709\u65f6\u4f1a\u53d1\u73b0\u63d0\u4f9b\u8f83\u77ed\u7684\u8868\u540d\u6216\u5217\u540d\u522b\u540d\u5f88\u6709\u7528\u3002.<\/p>\n
\u5728 SQL \u4e2d\uff0c\u60a8\u53ef\u4ee5\u901a\u8fc7\u5728 FROM \u5b50\u53e5\u4e2d\u7684\u6bcf\u4e2a\u8868\u5b9a\u4e49\u540e\u8ddf AS \u5173\u952e\u5b57\uff0c\u7136\u540e\u5728 AS \u5173\u952e\u5b57\u540e\u8ddf\u60a8\u9009\u62e9\u7684\u522b\u540d\u6765\u5b9e\u73b0\u8fd9\u4e00\u70b9\uff1a<\/p>\n
\nSELECT t1.column1, t2.column2\r\nFROM table1 AS t1 JOIN table2 AS t2\r\nON t1.related_column = t2.related_column;<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u6b64\u793a\u4f8b\u8bed\u6cd5\u5728 SELECT \u5b50\u53e5\u4e2d\u4f7f\u7528\u4e86\u522b\u540d\uff0c\u5373\u4f7f\u5b83\u4eec\u5e76\u672a\u5728 FROM \u5b50\u53e5\u4e4b\u524d\u5b9a\u4e49\u3002\u8fd9\u662f\u56e0\u4e3a\u5728 SQL \u67e5\u8be2\u4e2d\uff0c\u6267\u884c\u987a\u5e8f\u662f\u4ece FROM \u5b50\u53e5\u5f00\u59cb\u7684\u3002\u8fd9\u53ef\u80fd\u4f1a\u4ee4\u4eba\u56f0\u60d1\uff0c\u4f46\u8bb0\u4f4f\u8fd9\u4e00\u70b9\u5e76\u5728\u5f00\u59cb\u7f16\u5199\u67e5\u8be2\u4e4b\u524d\u8003\u8651\u522b\u540d\u975e\u5e38\u6709\u7528\u3002.<\/p>\n
\u4f8b\u5982\uff0c\u8fd0\u884c\u4ee5\u4e0b\u67e5\u8be2\uff0c\u5c06 Sales \u8868\u548c Products \u8868\u8fde\u63a5\u8d77\u6765\uff0c\u5e76\u5206\u522b\u7ed9\u5b83\u4eec\u8d4b\u4e88\u522b\u540d S \u548c P\uff1a<\/p>\n
\nSELECT S.saleID, S.quantity,\r\nP.productName,\r\n(P.price * S.quantity) AS revenue \r\nFROM sales AS S JOIN products AS P\r\nUSING (productID);<\/code><\/pre>\n<\/div>\n<\/div>\n\u8bf7\u6ce8\u610f\uff0c\u6b64\u793a\u4f8b\u521b\u5efa\u4e86\u7b2c\u4e09\u4e2a\u522b\u540d\u201c\u6536\u5165\u201d\uff0c\u7528\u4e8e\u8868\u793a\u201c\u9500\u552e\u201d\u8868\u4e2d\u201c\u91d1\u989d\u201d\u5217\u7684\u503c\u4e0e\u201c\u4ea7\u54c1\u201d\u8868\u4e2d\u201c\u4ef7\u683c\u201d\u5217\u4e2d\u5bf9\u5e94\u503c\u7684\u4e58\u79ef\u3002\u8fd9\u4ec5\u5728\u7ed3\u679c\u96c6\u7684\u5217\u540d\u4e2d\u53ef\u89c1\uff0c\u4f46\u63d0\u4f9b\u8fd9\u6837\u7684\u522b\u540d\u6709\u52a9\u4e8e\u4f20\u8fbe\u67e5\u8be2\u7ed3\u679c\u80cc\u540e\u7684\u542b\u4e49\u6216\u610f\u56fe\uff1a<\/div>\n\n\nOutput\r\n+--------+----------+-------------+---------+\r\n| saleID | quantity | productName | revenue |\r\n+--------+----------+-------------+---------+\r\n| 1 | 7 | widget | 132.93 |\r\n| 2 | 10 | whatzit | 299.90 |\r\n| 3 | 8 | gizmo | 115.92 |\r\n| 4 | 1 | thingamajig | 39.99 |\r\n| 5 | 5 | widget | 94.95 |\r\n| 6 | 1 | whatzit | 29.99 |\r\n| 7 | 3 | widget | 56.97 |\r\n| 8 | 4 | whatzit | 119.96 |\r\n+--------+----------+-------------+---------+\r\n8 rows in set (0.00 sec)<\/code><\/pre>\n<\/div>\n<\/div>\n\u8bf7\u6ce8\u610f\uff0c\u5b9a\u4e49\u522b\u540d\u65f6\uff0cAS \u5173\u952e\u5b57\u5728\u6280\u672f\u4e0a\u662f\u53ef\u9009\u7684\u3002\u524d\u9762\u7684\u793a\u4f8b\u4e5f\u53ef\u4ee5\u5199\u6210\uff1a<\/div>\n\n\nSELECT S.saleID, S.quantity, P.productName, (P.price * S.quantity) revenue \r\nFROM sales S JOIN products P\r\nUSING (productID);<\/code><\/pre>\n<\/div>\n<\/div>\n\n\u867d\u7136\u5b9a\u4e49\u522b\u540d\u65f6\u5e76\u975e\u5fc5\u987b\u4f7f\u7528 AS \u5173\u952e\u5b57\uff0c\u4f46\u5efa\u8bae\u6700\u597d\u8fd8\u662f\u4f7f\u7528\u5b83\u3002\u8fd9\u6837\u505a\u6709\u52a9\u4e8e\u6e05\u6670\u5730\u8868\u8fbe\u67e5\u8be2\u610f\u56fe\uff0c\u5e76\u63d0\u9ad8\u67e5\u8be2\u7684\u53ef\u8bfb\u6027\u3002.<\/p>\n
\u7ed3\u679c<\/h2>\n
\u901a\u8fc7\u9605\u8bfb\u672c\u6307\u5357\uff0c\u60a8\u5b66\u4e60\u4e86\u5982\u4f55\u4f7f\u7528 JOIN \u64cd\u4f5c\u5c06\u591a\u4e2a\u8868\u5408\u5e76\u5230\u4e00\u4e2a\u67e5\u8be2\u7ed3\u679c\u96c6\u4e2d\u3002\u867d\u7136\u8fd9\u91cc\u5c55\u793a\u7684\u547d\u4ee4\u9002\u7528\u4e8e\u5927\u591a\u6570\u5173\u7cfb\u578b\u6570\u636e\u5e93\uff0c\u4f46\u8bf7\u6ce8\u610f\uff0c\u6bcf\u4e2a SQL \u6570\u636e\u5e93\u90fd\u4f7f\u7528\u5176\u72ec\u7279\u7684\u8bed\u8a00\u5b9e\u73b0\u3002\u60a8\u5e94\u8be5\u53c2\u8003\u6570\u636e\u5e93\u7ba1\u7406\u7cfb\u7edf (DBMS) \u6587\u6863\uff0c\u4ee5\u83b7\u53d6\u6bcf\u4e2a\u547d\u4ee4\u53ca\u5176\u6240\u6709\u9009\u9879\u7684\u66f4\u5b8c\u6574\u8bf4\u660e\u3002.<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"\u5f15\u8a00 \u8bb8\u591a\u6570\u636e\u5e93\u8bbe\u8ba1\u90fd\u57fa\u4e8e\u7279\u5b9a\u6570\u636e\u70b9\u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u5c06\u4fe1\u606f\u7ec4\u7ec7\u6210\u8868\u683c\u3002","protected":false},"author":1,"featured_media":16027,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_focuskw":"\u0646\u062d\u0648\u0647 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 Joins \u062f\u0631 SQL","_yoast_wpseo_title":"","_yoast_wpseo_metadesc":"","_yoast_wpseo_canonical":"","_yoast_wpseo_opengraph-description":"","_yoast_wpseo_opengraph-image":"","_yoast_wpseo_twitter-description":"","_yoast_wpseo_twitter-image":"","_yoast_wpseo_focuskeywords":"","_yoast_wpseo_primary_category":"193","footnotes":""},"categories":[193,349],"tags":[403,391],"class_list":{"0":"post-15949","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-tutorials","8":"category-database","9":"tag-data-base","10":"tag-mysql"},"yoast_head":"\n
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