{"id":11448,"date":"2025-06-12T10:42:43","date_gmt":"2025-06-12T02:42:43","guid":{"rendered":"https:\/\/egonlin.com\/?p=11448"},"modified":"2025-06-12T16:26:33","modified_gmt":"2025-06-12T08:26:33","slug":"sql%e9%80%bb%e8%be%91%e6%9f%a5%e8%af%a2%e8%af%ad%e5%8f%a5%e6%89%a7%e8%a1%8c%e9%a1%ba%e5%ba%8f-2","status":"publish","type":"post","link":"https:\/\/egonlin.com\/?p=11448","title":{"rendered":"SQL\u903b\u8f91\u67e5\u8be2\u8bed\u53e5\u6267\u884c\u987a\u5e8f"},"content":{"rendered":"

\u4e00 SELECT\u8bed\u53e5\u5173\u952e\u5b57\u7684\u5b9a\u4e49\u987a\u5e8f<\/h3>\n
\n
SELECT DISTINCT <select_list>\r\nFROM <left_table>\r\n<join_type> JOIN <right_table>\r\nON <join_condition>\r\nWHERE <where_condition>\r\nGROUP BY <group_by_list>\r\nHAVING <having_condition>\r\nORDER BY <order_by_condition>\r\nLIMIT <limit_number><\/pre>\n<\/div>\n
\u4e8c SELECT\u8bed\u53e5\u5173\u952e\u5b57\u7684\u6267\u884c\u987a\u5e8f<\/h3>\n
\n
(7)     SELECT \r\n(8)     DISTINCT <select_list>\r\n(1)     FROM <left_table>\r\n(3)     <join_type> JOIN <right_table>\r\n(2)     ON <join_condition>\r\n(4)     WHERE <where_condition>\r\n(5)     GROUP BY <group_by_list>\r\n(6)     HAVING <having_condition>\r\n(9)     ORDER BY <order_by_condition>\r\n(10)    LIMIT <limit_number><\/pre>\n<\/div>\n
\u4e09 \u51c6\u5907\u8868\u548c\u6570\u636e<\/h3>\n
1. \u65b0\u5efa\u4e00\u4e2a\u6d4b\u8bd5\u6570\u636e\u5e93TestDB\uff1b<\/p>\n
\n
create database TestDB;<\/pre>\n<\/div>\n
2.\u521b\u5efa\u6d4b\u8bd5\u8868table1\u548ctable2\uff1b<\/p>\n
\n
CREATE TABLE table1\r\n (\r\n     customer_id VARCHAR(10) NOT NULL,\r\n     city VARCHAR(10) NOT NULL,\r\n     PRIMARY KEY(customer_id)\r\n )ENGINE=INNODB DEFAULT CHARSET=UTF8;\r\n\r\n CREATE TABLE table2\r\n (\r\n     order_id INT NOT NULL auto_increment,\r\n     customer_id VARCHAR(10),\r\n     PRIMARY KEY(order_id)\r\n )ENGINE=INNODB DEFAULT CHARSET=UTF8;<\/pre>\n<\/div>\n
3.\u63d2\u5165\u6d4b\u8bd5\u6570\u636e\uff1b<\/p>\n
\n
 INSERT INTO table1(customer_id,city) VALUES('163','hangzhou');\r\n INSERT INTO table1(customer_id,city) VALUES('9you','shanghai');\r\n INSERT INTO table1(customer_id,city) VALUES('tx','hangzhou');\r\n INSERT INTO table1(customer_id,city) VALUES('baidu','hangzhou');\r\n\r\n INSERT INTO table2(customer_id) VALUES('163');\r\n INSERT INTO table2(customer_id) VALUES('163');\r\n INSERT INTO table2(customer_id) VALUES('9you');\r\n INSERT INTO table2(customer_id) VALUES('9you');\r\n INSERT INTO table2(customer_id) VALUES('9you');\r\n INSERT INTO table2(customer_id) VALUES('tx');\r\n INSERT INTO table2(customer_id) VALUES(NULL);<\/pre>\n<\/div>\n
\u51c6\u5907\u5de5\u4f5c\u505a\u5b8c\u4ee5\u540e\uff0ctable1\u548ctable2\u770b\u8d77\u6765\u5e94\u8be5\u50cf\u4e0b\u9762\u8fd9\u6837\uff1a<\/p>\n
\n
mysql> select * from table1;\r\n +-------------+----------+\r\n | customer_id | city     |\r\n +-------------+----------+\r\n | 163         | hangzhou |\r\n | 9you        | shanghai |\r\n | baidu       | hangzhou |\r\n | tx          | hangzhou |\r\n +-------------+----------+\r\n 4 rows in set (0.00 sec)\r\n\r\n mysql> select * from table2;\r\n +----------+-------------+\r\n | order_id | customer_id |\r\n +----------+-------------+\r\n |        1 | 163         |\r\n |        2 | 163         |\r\n |        3 | 9you        |\r\n |        4 | 9you        |\r\n |        5 | 9you        |\r\n |        6 | tx          |\r\n |        7 | NULL        |\r\n +----------+-------------+\r\n 7 rows in set (0.00 sec)<\/pre>\n<\/div>\n
\u56db \u51c6\u5907SQL\u903b\u8f91\u67e5\u8be2\u6d4b\u8bd5\u8bed\u53e5<\/h3>\n
\n
#\u67e5\u8be2\u6765\u81ea\u676d\u5dde\uff0c\u5e76\u4e14\u8ba2\u5355\u6570\u5c11\u4e8e2\u7684\u5ba2\u6237\u3002\r\n SELECT a.customer_id, COUNT(b.order_id) as total_orders\r\n FROM table1 AS a\r\n LEFT JOIN table2 AS b\r\n ON a.customer_id = b.customer_id\r\n WHERE a.city = 'hangzhou'\r\n GROUP BY a.customer_id\r\n HAVING count(b.order_id) < 2\r\n ORDER BY total_orders DESC;<\/pre>\n<\/div>\n
\u4e94 \u6267\u884c\u987a\u5e8f\u5206\u6790<\/h3>\n
\u5728\u8fd9\u4e9bSQL\u8bed\u53e5\u7684\u6267\u884c\u8fc7\u7a0b\u4e2d\uff0c\u90fd\u4f1a\u4ea7\u751f\u4e00\u4e2a\u865a\u62df\u8868\uff0c\u7528\u6765\u4fdd\u5b58SQL\u8bed\u53e5\u7684\u6267\u884c\u7ed3\u679c\uff08\u8fd9\u662f\u91cd\u70b9\uff09\uff0c\u6211\u73b0\u5728\u5c31\u6765\u8ddf\u8e2a\u8fd9\u4e2a\u865a\u62df\u8868\u7684\u53d8\u5316\uff0c\u5f97\u5230\u6700\u7ec8\u7684\u67e5\u8be2\u7ed3\u679c\u7684\u8fc7\u7a0b\uff0c\u6765\u5206\u6790\u6574\u4e2aSQL\u903b\u8f91\u67e5\u8be2\u7684\u6267\u884c\u987a\u5e8f\u548c\u8fc7\u7a0b\u3002<\/p>\n
\u6267\u884cFROM\u8bed\u53e5<\/strong><\/p>\n
\u7b2c\u4e00\u6b65\uff0c\u6267\u884cFROM<\/code>\u8bed\u53e5\u3002\u6211\u4eec\u9996\u5148\u9700\u8981\u77e5\u9053\u6700\u5f00\u59cb\u4ece\u54ea\u4e2a\u8868\u5f00\u59cb\u7684\uff0c\u8fd9\u5c31\u662fFROM<\/code>\u544a\u8bc9\u6211\u4eec\u7684\u3002\u73b0\u5728\u6709\u4e86<left_table><\/code>\u548c<right_table><\/code>\u4e24\u4e2a\u8868\uff0c\u6211\u4eec\u5230\u5e95\u4ece\u54ea\u4e2a\u8868\u5f00\u59cb\uff0c\u8fd8\u662f\u4ece\u4e24\u4e2a\u8868\u8fdb\u884c\u67d0\u79cd\u8054\u7cfb\u4ee5\u540e\u518d\u5f00\u59cb\u5462\uff1f\u5b83\u4eec\u4e4b\u95f4\u5982\u4f55\u4ea7\u751f\u8054\u7cfb\u5462\uff1f\u2014\u2014\u7b1b\u5361\u5c14\u79ef<\/em><\/p>\n
\u5173\u4e8e\u4ec0\u4e48\u662f\u7b1b\u5361\u5c14\u79ef\uff0c\u8bf7\u81ea\u884cGoogle\u8865\u8111\u3002\u7ecf\u8fc7FROM\u8bed\u53e5\u5bf9\u4e24\u4e2a\u8868\u6267\u884c\u7b1b\u5361\u5c14\u79ef\uff0c\u4f1a\u5f97\u5230\u4e00\u4e2a\u865a\u62df\u8868\uff0c\u6682\u4e14\u53ebVT1\uff08vitual table 1\uff09\uff0c\u5185\u5bb9\u5982\u4e0b\uff1a<\/em><\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 9you        | shanghai |        1 | 163         |\r\n| baidu       | hangzhou |        1 | 163         |\r\n| tx          | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| 9you        | shanghai |        2 | 163         |\r\n| baidu       | hangzhou |        2 | 163         |\r\n| tx          | hangzhou |        2 | 163         |\r\n| 163         | hangzhou |        3 | 9you        |\r\n| 9you        | shanghai |        3 | 9you        |\r\n| baidu       | hangzhou |        3 | 9you        |\r\n| tx          | hangzhou |        3 | 9you        |\r\n| 163         | hangzhou |        4 | 9you        |\r\n| 9you        | shanghai |        4 | 9you        |\r\n| baidu       | hangzhou |        4 | 9you        |\r\n| tx          | hangzhou |        4 | 9you        |\r\n| 163         | hangzhou |        5 | 9you        |\r\n| 9you        | shanghai |        5 | 9you        |\r\n| baidu       | hangzhou |        5 | 9you        |\r\n| tx          | hangzhou |        5 | 9you        |\r\n| 163         | hangzhou |        6 | tx          |\r\n| 9you        | shanghai |        6 | tx          |\r\n| baidu       | hangzhou |        6 | tx          |\r\n| tx          | hangzhou |        6 | tx          |\r\n| 163         | hangzhou |        7 | NULL        |\r\n| 9you        | shanghai |        7 | NULL        |\r\n| baidu       | hangzhou |        7 | NULL        |\r\n| tx          | hangzhou |        7 | NULL        |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
\u603b\u5171\u670928\uff08table1\u7684\u8bb0\u5f55\u6761\u6570 * table2\u7684\u8bb0\u5f55\u6761\u6570\uff09\u6761\u8bb0\u5f55\u3002\u8fd9\u5c31\u662fVT1\u7684\u7ed3\u679c\uff0c\u63a5\u4e0b\u6765\u7684\u64cd\u4f5c\u5c31\u5728VT1\u7684\u57fa\u7840\u4e0a\u8fdb\u884c\u3002<\/em><\/p>\n
\u6267\u884cON\u8fc7\u6ee4<\/strong><\/p>\n
\u6267\u884c\u5b8c\u7b1b\u5361\u5c14\u79ef\u4ee5\u540e\uff0c\u63a5\u7740\u5c31\u8fdb\u884cON a.customer_id = b.customer_id<\/code>\u6761\u4ef6\u8fc7\u6ee4\uff0c\u6839\u636eON<\/code>\u4e2d\u6307\u5b9a\u7684\u6761\u4ef6\uff0c\u53bb\u6389\u90a3\u4e9b\u4e0d\u7b26\u5408\u6761\u4ef6\u7684\u6570\u636e\uff0c\u5f97\u5230VT2\u8868\uff0c\u5185\u5bb9\u5982\u4e0b\uff1a<\/em><\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| 9you        | shanghai |        3 | 9you        |\r\n| 9you        | shanghai |        4 | 9you        |\r\n| 9you        | shanghai |        5 | 9you        |\r\n| tx          | hangzhou |        6 | tx          |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
VT2\u5c31\u662f\u7ecf\u8fc7ON<\/code>\u6761\u4ef6\u7b5b\u9009\u4ee5\u540e\u5f97\u5230\u7684\u6709\u7528\u6570\u636e\uff0c\u800c\u63a5\u4e0b\u6765\u7684\u64cd\u4f5c\u5c06\u5728VT2\u7684\u57fa\u7840\u4e0a\u7ee7\u7eed\u8fdb\u884c\u3002<\/em><\/p>\n
\u6dfb\u52a0\u5916\u90e8\u884c<\/strong><\/p>\n
\u8fd9\u4e00\u6b65\u53ea\u6709\u5728\u8fde\u63a5\u7c7b\u578b\u4e3aOUTER JOIN<\/code>\u65f6\u624d\u53d1\u751f\uff0c\u5982LEFT OUTER JOIN<\/code>\u3001RIGHT OUTER JOIN<\/code>\u548cFULL OUTER JOIN<\/code>\u3002\u5728\u5927\u591a\u6570\u7684\u65f6\u5019\uff0c\u6211\u4eec\u90fd\u662f\u4f1a\u7701\u7565\u6389OUTER<\/code>\u5173\u952e\u5b57\u7684\uff0c\u4f46OUTER<\/code>\u8868\u793a\u7684\u5c31\u662f\u5916\u90e8\u884c\u7684\u6982\u5ff5\u3002<\/em><\/p>\n
LEFT OUTER JOIN<\/code>\u628a\u5de6\u8868\u8bb0\u4e3a\u4fdd\u7559\u8868\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u4e3a\uff1a<\/em><\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| 9you        | shanghai |        3 | 9you        |\r\n| 9you        | shanghai |        4 | 9you        |\r\n| 9you        | shanghai |        5 | 9you        |\r\n| tx          | hangzhou |        6 | tx          |\r\n| baidu       | hangzhou |     NULL | NULL        |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
RIGHT OUTER JOIN<\/code>\u628a\u53f3\u8868\u8bb0\u4e3a\u4fdd\u7559\u8868\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u4e3a\uff1a<\/em><\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| 9you        | shanghai |        3 | 9you        |\r\n| 9you        | shanghai |        4 | 9you        |\r\n| 9you        | shanghai |        5 | 9you        |\r\n| tx          | hangzhou |        6 | tx          |\r\n| NULL        | NULL     |        7 | NULL        |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
FULL OUTER JOIN<\/code>\u628a\u5de6\u53f3\u8868\u90fd\u4f5c\u4e3a\u4fdd\u7559\u8868\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u4e3a\uff1a<\/em><\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| 9you        | shanghai |        3 | 9you        |\r\n| 9you        | shanghai |        4 | 9you        |\r\n| 9you        | shanghai |        5 | 9you        |\r\n| tx          | hangzhou |        6 | tx          |\r\n| baidu       | hangzhou |     NULL | NULL        |\r\n| NULL        | NULL     |        7 | NULL        |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
\u6dfb\u52a0\u5916\u90e8\u884c\u7684\u5de5\u4f5c\u5c31\u662f\u5728VT2\u8868\u7684\u57fa\u7840\u4e0a\u6dfb\u52a0\u4fdd\u7559\u8868\u4e2d\u88ab\u8fc7\u6ee4\u6761\u4ef6\u8fc7\u6ee4\u6389\u7684\u6570\u636e\uff0c\u975e\u4fdd\u7559\u8868\u4e2d\u7684\u6570\u636e\u88ab\u8d4b\u4e88NULL\u503c\uff0c\u6700\u540e\u751f\u6210\u865a\u62df\u8868VT3\u3002<\/em><\/p>\n
\u7531\u4e8e\u6211\u5728\u51c6\u5907\u7684\u6d4b\u8bd5SQL\u67e5\u8be2\u903b\u8f91\u8bed\u53e5\u4e2d\u4f7f\u7528\u7684\u662fLEFT JOIN<\/code>\uff0c\u8fc7\u6ee4\u6389\u4e86\u4ee5\u4e0b\u8fd9\u6761\u6570\u636e\uff1a<\/em><\/p>\n
\n
| baidu       | hangzhou |     NULL | NULL        |<\/pre>\n<\/div>\n
\u73b0\u5728\u5c31\u628a\u8fd9\u6761\u6570\u636e\u6dfb\u52a0\u5230VT2\u8868\u4e2d\uff0c\u5f97\u5230\u7684VT3\u8868\u5982\u4e0b\uff1a<\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| 9you        | shanghai |        3 | 9you        |\r\n| 9you        | shanghai |        4 | 9you        |\r\n| 9you        | shanghai |        5 | 9you        |\r\n| tx          | hangzhou |        6 | tx          |\r\n| baidu       | hangzhou |     NULL | NULL        |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
\u63a5\u4e0b\u6765\u7684\u64cd\u4f5c\u90fd\u4f1a\u5728\u8be5VT3\u8868\u4e0a\u8fdb\u884c\u3002<\/em><\/p>\n
\u6267\u884cWHERE\u8fc7\u6ee4<\/strong><\/p>\n
\u5bf9\u6dfb\u52a0\u5916\u90e8\u884c\u5f97\u5230\u7684VT3\u8fdb\u884cWHERE\u8fc7\u6ee4\uff0c\u53ea\u6709\u7b26\u5408<where_condition>\u7684\u8bb0\u5f55\u624d\u4f1a\u8f93\u51fa\u5230\u865a\u62df\u8868VT4\u4e2d\u3002\u5f53\u6211\u4eec\u6267\u884cWHERE a.city = 'hangzhou'<\/code>\u7684\u65f6\u5019\uff0c\u5c31\u4f1a\u5f97\u5230\u4ee5\u4e0b\u5185\u5bb9\uff0c\u5e76\u5b58\u5728\u865a\u62df\u8868VT4\u4e2d\uff1a<\/em><\/p>\n
\n
+-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| 163         | hangzhou |        2 | 163         |\r\n| tx          | hangzhou |        6 | tx          |\r\n| baidu       | hangzhou |     NULL | NULL        |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
\u4f46\u662f\u5728\u4f7f\u7528WHERE\u5b50\u53e5\u65f6\uff0c\u9700\u8981\u6ce8\u610f\u4ee5\u4e0b\u4e24\u70b9\uff1a<\/p>\n
    \n
  1. \u7531\u4e8e\u6570\u636e\u8fd8\u6ca1\u6709\u5206\u7ec4\uff0c\u56e0\u6b64\u73b0\u5728\u8fd8\u4e0d\u80fd\u5728WHERE\u8fc7\u6ee4\u5668\u4e2d\u4f7f\u7528where_condition=MIN(col)<\/code>\u8fd9\u7c7b\u5bf9\u5206\u7ec4\u7edf\u8ba1\u7684\u8fc7\u6ee4\uff1b<\/li>\n
  2. \u7531\u4e8e\u8fd8\u6ca1\u6709\u8fdb\u884c\u5217\u7684\u9009\u53d6\u64cd\u4f5c\uff0c\u56e0\u6b64\u5728SELECT\u4e2d\u4f7f\u7528\u5217\u7684\u522b\u540d\u4e5f\u662f\u4e0d\u88ab\u5141\u8bb8\u7684\uff0c\u5982\uff1aSELECT city as c FROM t WHERE c='shanghai';<\/code>\u662f\u4e0d\u5141\u8bb8\u51fa\u73b0\u7684\u3002<\/li>\n<\/ol>\n
    \u6267\u884cGROUP BY\u5206\u7ec4<\/strong><\/p>\n
    GROU BY<\/code>\u5b50\u53e5\u4e3b\u8981\u662f\u5bf9\u4f7f\u7528WHERE<\/code>\u5b50\u53e5\u5f97\u5230\u7684\u865a\u62df\u8868\u8fdb\u884c\u5206\u7ec4\u64cd\u4f5c\u3002\u6211\u4eec\u6267\u884c\u6d4b\u8bd5\u8bed\u53e5\u4e2d\u7684GROUP BY a.customer_id<\/code>\uff0c\u5c31\u4f1a\u5f97\u5230\u4ee5\u4e0b\u5185\u5bb9(\u9ed8\u8ba4\u53ea\u663e\u793a\u7ec4\u5185\u7b2c\u4e00\u6761)\uff1a<\/em><\/p>\n
    \n
    +-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| 163         | hangzhou |        1 | 163         |\r\n| baidu       | hangzhou |     NULL | NULL        |\r\n| tx          | hangzhou |        6 | tx          |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
    \u5f97\u5230\u7684\u5185\u5bb9\u4f1a\u5b58\u5165\u865a\u62df\u8868VT5\u4e2d\uff0c\u6b64\u65f6\uff0c\u6211\u4eec\u5c31\u5f97\u5230\u4e86\u4e00\u4e2aVT5\u865a\u62df\u8868\uff0c\u63a5\u4e0b\u6765\u7684\u64cd\u4f5c\u90fd\u4f1a\u5728\u8be5\u8868\u4e0a\u5b8c\u6210\u3002<\/em><\/p>\n
    \u6267\u884cHAVING\u8fc7\u6ee4<\/strong><\/p>\n
    HAVING<\/code>\u5b50\u53e5\u4e3b\u8981\u548cGROUP BY<\/code>\u5b50\u53e5\u914d\u5408\u4f7f\u7528\uff0c\u5bf9\u5206\u7ec4\u5f97\u5230\u7684VT5\u865a\u62df\u8868\u8fdb\u884c\u6761\u4ef6\u8fc7\u6ee4\u3002\u5f53\u6211\u6267\u884c\u6d4b\u8bd5\u8bed\u53e5\u4e2d\u7684HAVING count(b.order_id) < 2<\/code>\u65f6\uff0c\u5c06\u5f97\u5230\u4ee5\u4e0b\u5185\u5bb9\uff1a<\/em><\/p>\n
    \n
    +-------------+----------+----------+-------------+\r\n| customer_id | city     | order_id | customer_id |\r\n+-------------+----------+----------+-------------+\r\n| baidu       | hangzhou |     NULL | NULL        |\r\n| tx          | hangzhou |        6 | tx          |\r\n+-------------+----------+----------+-------------+<\/pre>\n<\/div>\n
    \u8fd9\u5c31\u662f\u865a\u62df\u8868VT6\u3002<\/em><\/p>\n
    SELECT\u5217\u8868<\/strong><\/p>\n
    \u73b0\u5728\u624d\u4f1a\u6267\u884c\u5230SELECT<\/code>\u5b50\u53e5\uff0c\u4e0d\u8981\u4ee5\u4e3aSELECT<\/code>\u5b50\u53e5\u88ab\u5199\u5728\u7b2c\u4e00\u884c\uff0c\u5c31\u662f\u7b2c\u4e00\u4e2a\u88ab\u6267\u884c\u7684\u3002<\/em><\/p>\n
    \u6211\u4eec\u6267\u884c\u6d4b\u8bd5\u8bed\u53e5\u4e2d\u7684SELECT a.customer_id, COUNT(b.order_id) as total_orders<\/code>\uff0c\u4ece\u865a\u62df\u8868VT6\u4e2d\u9009\u62e9\u51fa\u6211\u4eec\u9700\u8981\u7684\u5185\u5bb9\u3002\u6211\u4eec\u5c06\u5f97\u5230\u4ee5\u4e0b\u5185\u5bb9\uff1a<\/em><\/p>\n
    \n
    +-------------+--------------+\r\n| customer_id | total_orders |\r\n+-------------+--------------+\r\n| baidu       |            0 |\r\n| tx          |            1 |\r\n+-------------+--------------+<\/pre>\n<\/div>\n
    \u8fd8\u6ca1\u6709\u5b8c\uff0c\u8fd9\u53ea\u662f\u865a\u62df\u8868VT7\u3002<\/em><\/p>\n
    \u6267\u884cDISTINCT\u5b50\u53e5<\/strong><\/p>\n
    \u5982\u679c\u5728\u67e5\u8be2\u4e2d\u6307\u5b9a\u4e86DISTINCT<\/code>\u5b50\u53e5\uff0c\u5219\u4f1a\u521b\u5efa\u4e00\u5f20\u5185\u5b58\u4e34\u65f6\u8868\uff08\u5982\u679c\u5185\u5b58\u653e\u4e0d\u4e0b\uff0c\u5c31\u9700\u8981\u5b58\u653e\u5728\u786c\u76d8\u4e86\uff09\u3002\u8fd9\u5f20\u4e34\u65f6\u8868\u7684\u8868\u7ed3\u6784\u548c\u4e0a\u4e00\u6b65\u4ea7\u751f\u7684\u865a\u62df\u8868VT7\u662f\u4e00\u6837\u7684\uff0c\u4e0d\u540c\u7684\u662f\u5bf9\u8fdb\u884cDISTINCT\u64cd\u4f5c\u7684\u5217\u589e\u52a0\u4e86\u4e00\u4e2a\u552f\u4e00\u7d22\u5f15\uff0c\u4ee5\u6b64\u6765\u9664\u91cd\u590d\u6570\u636e\u3002<\/em><\/p>\n
    \u7531\u4e8e\u6211\u7684\u6d4b\u8bd5SQL\u8bed\u53e5\u4e2d\u5e76\u6ca1\u6709\u4f7f\u7528DISTINCT\uff0c\u6240\u4ee5\uff0c\u5728\u8be5\u67e5\u8be2\u4e2d\uff0c\u8fd9\u4e00\u6b65\u4e0d\u4f1a\u751f\u6210\u4e00\u4e2a\u865a\u62df\u8868\u3002<\/em><\/p>\n
    \u6267\u884cORDER BY\u5b50\u53e5<\/strong><\/p>\n
    \u5bf9\u865a\u62df\u8868\u4e2d\u7684\u5185\u5bb9\u6309\u7167\u6307\u5b9a\u7684\u5217\u8fdb\u884c\u6392\u5e8f\uff0c\u7136\u540e\u8fd4\u56de\u4e00\u4e2a\u65b0\u7684\u865a\u62df\u8868\uff0c\u6211\u4eec\u6267\u884c\u6d4b\u8bd5SQL\u8bed\u53e5\u4e2d\u7684ORDER BY total_orders DESC<\/code>\uff0c\u5c31\u4f1a\u5f97\u5230\u4ee5\u4e0b\u5185\u5bb9\uff1a<\/em><\/p>\n
    \n
    +-------------+--------------+\r\n| customer_id | total_orders |\r\n+-------------+--------------+\r\n| tx          |            1 |\r\n| baidu       |            0 |\r\n+-------------+--------------+<\/pre>\n<\/div>\n
    \u53ef\u4ee5\u770b\u5230\u8fd9\u662f\u5bf9total_orders\u5217\u8fdb\u884c\u964d\u5e8f\u6392\u5217\u7684\u3002\u4e0a\u8ff0\u7ed3\u679c\u4f1a\u5b58\u50a8\u5728VT8\u4e2d\u3002<\/em><\/p>\n
    \u6267\u884cLIMIT\u5b50\u53e5<\/strong><\/p>\n
    LIMIT<\/code>\u5b50\u53e5\u4ece\u4e0a\u4e00\u6b65\u5f97\u5230\u7684VT8\u865a\u62df\u8868\u4e2d\u9009\u51fa\u4ece\u6307\u5b9a\u4f4d\u7f6e\u5f00\u59cb\u7684\u6307\u5b9a\u884c\u6570\u636e\u3002\u5bf9\u4e8e\u6ca1\u6709\u5e94\u7528ORDER BY\u7684LIMIT\u5b50\u53e5\uff0c\u5f97\u5230\u7684\u7ed3\u679c\u540c\u6837\u662f\u65e0\u5e8f\u7684\uff0c\u6240\u4ee5\uff0c\u5f88\u591a\u65f6\u5019\uff0c\u6211\u4eec\u90fd\u4f1a\u770b\u5230LIMIT\u5b50\u53e5\u4f1a\u548cORDER BY\u5b50\u53e5\u4e00\u8d77\u4f7f\u7528\u3002<\/em><\/p>\n
    MySQL\u6570\u636e\u5e93\u7684LIMIT\u652f\u6301\u5982\u4e0b\u5f62\u5f0f\u7684\u9009\u62e9\uff1a<\/em><\/p>\n
    \n
    LIMIT n, m<\/pre>\n<\/div>\n
    \u8868\u793a\u4ece\u7b2cn\u6761\u8bb0\u5f55\u5f00\u59cb\u9009\u62e9m\u6761\u8bb0\u5f55\u3002\u800c\u5f88\u591a\u5f00\u53d1\u4eba\u5458\u559c\u6b22\u4f7f\u7528\u8be5\u8bed\u53e5\u6765\u89e3\u51b3\u5206\u9875\u95ee\u9898\u3002\u5bf9\u4e8e\u5c0f\u6570\u636e\uff0c\u4f7f\u7528LIMIT\u5b50\u53e5\u6ca1\u6709\u4efb\u4f55\u95ee\u9898\uff0c\u5f53\u6570\u636e\u91cf\u975e\u5e38\u5927\u7684\u65f6\u5019\uff0c\u4f7f\u7528LIMIT n, m<\/code>\u662f\u975e\u5e38\u4f4e\u6548\u7684\u3002\u56e0\u4e3aLIMIT\u7684\u673a\u5236\u662f\u6bcf\u6b21\u90fd\u662f\u4ece\u5934\u5f00\u59cb\u626b\u63cf\uff0c\u5982\u679c\u9700\u8981\u4ece\u7b2c60\u4e07\u884c\u5f00\u59cb\uff0c\u8bfb\u53d63\u6761\u6570\u636e\uff0c\u5c31\u9700\u8981\u5148\u626b\u63cf\u5b9a\u4f4d\u523060\u4e07\u884c\uff0c\u7136\u540e\u518d\u8fdb\u884c\u8bfb\u53d6\uff0c\u800c\u626b\u63cf\u7684\u8fc7\u7a0b\u662f\u4e00\u4e2a\u975e\u5e38\u4f4e\u6548\u7684\u8fc7\u7a0b\u3002\u6240\u4ee5\uff0c\u5bf9\u4e8e\u5927\u6570\u636e\u5904\u7406\u65f6\uff0c\u662f\u975e\u5e38\u6709\u5fc5\u8981\u5728\u5e94\u7528\u5c42\u5efa\u7acb\u4e00\u5b9a\u7684\u7f13\u5b58\u673a\u5236\uff08\u73b0\u5728\u7684\u5927\u6570\u636e\u5904\u7406\uff0c\u5927\u90fd\u4f7f\u7528\u7f13\u5b58\uff09<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"
    \u4e00 SELECT\u8bed\u53e5\u5173\u952e\u5b57\u7684\u5b9a\u4e49\u987a\u5e8f SELECT DISTINCT <select_list>  […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/11448"}],"collection":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=11448"}],"version-history":[{"count":1,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/11448\/revisions"}],"predecessor-version":[{"id":11449,"href":"https:\/\/egonlin.com\/index.php?rest_route=\/wp\/v2\/posts\/11448\/revisions\/11449"}],"wp:attachment":[{"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11448"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11448"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/egonlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11448"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}