{"id":87,"date":"2023-05-22T20:47:04","date_gmt":"2023-05-22T12:47:04","guid":{"rendered":"https:\/\/jiachen.de.cool\/blog\/?p=87"},"modified":"2023-05-22T20:47:04","modified_gmt":"2023-05-22T12:47:04","slug":"%e6%95%b0%e6%8d%ae%e6%9f%a5%e8%af%a2%e8%af%ad%e8%a8%80dql","status":"publish","type":"post","link":"https:\/\/jiachen.de.cool\/blog\/2023\/05\/22\/%e6%95%b0%e6%8d%ae%e6%9f%a5%e8%af%a2%e8%af%ad%e8%a8%80dql\/","title":{"rendered":"\u6570\u636e\u67e5\u8be2\u8bed\u8a00DQL"},"content":{"rendered":"\n

Data Query Language \u57fa\u672c\u7ed3\u6784\u662f\u7531 select<\u5b57\u6bb5>from<\u8868\u6216\u89c6\u56fe>where<\u67e5\u8be2\u6761\u4ef6>\u7ec4\u6210\u3002<\/p>\n\n\n\n

mysql> use learning;\r\nDatabase changed\r\nmysql> show tables;\r\n+--------------------+\r\n| Tables_in_learning |\r\n+--------------------+\r\n| houses             |\r\n+--------------------+\r\n1 row in set (0.02 sec)\r\n\r\nmysql> desc houses;\r\n+-----------------+--------------+------+-----+---------+-------+\r\n| Field           | Type         | Null | Key | Default | Extra |\r\n+-----------------+--------------+------+-----+---------+-------+\r\n| name            | varchar(100) | NO   |     | NULL    |       |\r\n| house_location  | varchar(100) | NO   |     | NULL    |       |\r\n| purchasing_year | varchar(100) | NO   |     | NULL    |       |\r\n+-----------------+--------------+------+-----+---------+-------+\r\n3 rows in set (0.01 sec)\r\n\r\nmysql> insert into houses (name,house_location,purchasing_year) values ('\u7532','\u5929\u6cb3',1997);\/*\u5411\u8868\u683c\u4e2d\u63d2\u5165\u65b0\u7684\u884c*\/\r\nQuery OK, 1 row affected (0.12 sec)\r\n\r\nmysql> insert into houses (name,house_location,purchasing_year) values ('\u7532','\u5929\u6cb3',1998);\r\nQuery OK, 1 row affected (0.07 sec)\r\n\r\nmysql> select name,house_location,purchasing_year from houses;\r\n+------+----------------+-----------------+\r\n| name | house_location | purchasing_year |\r\n+------+----------------+-----------------+\r\n| \u7532   | \u5929\u6cb3           | 1997            |\r\n| \u7532   | \u5929\u6cb3           | 1998            |\r\n+------+----------------+-----------------+\r\n2 rows in set (0.00 sec)\r\n\r\nmysql> select name,house_location,purchasing_year from houses where name='\u7532';\r\n+------+----------------+-----------------+\r\n| name | house_location | purchasing_year |\r\n+------+----------------+-----------------+\r\n| \u7532   | \u5929\u6cb3           | 1997            |\r\n| \u7532   | \u5929\u6cb3           | 1998            |\r\n+------+----------------+-----------------+\r\n2 rows in set (0.00 sec)\r\n\r\nmysql> select * from houses;\r\n+------+----------------+-----------------+\r\n| name | house_location | purchasing_year |\r\n+------+----------------+-----------------+\r\n| \u7532   | \u5929\u6cb3           | 1997            |\r\n| \u7532   | \u5929\u6cb3           | 1998            |\r\n+------+----------------+-----------------+\r\n2 rows in set (0.00 sec)\r\n\r\nmysql> select name from houses;\r\n+------+\r\n| name |\r\n+------+\r\n| \u7532   |\r\n| \u7532   |\r\n+------+\r\n2 rows in set (0.00 sec)\r\n\r\nmysql> select * from houses where name='ab';\r\nEmpty set (0.00 sec)\r\n\r\nmysql> create view housesview as select * from houses;\/*\u521b\u5efa\u89c6\u56fe*\/\r\nQuery OK, 0 rows affected (0.14 sec)\r\n\r\nmysql> select * from housesview;\r\n+------+----------------+-----------------+\r\n| name | house_location | purchasing_year |\r\n+------+----------------+-----------------+\r\n| \u7532   | \u5929\u6cb3           | 1997            |\r\n| \u7532   | \u5929\u6cb3           | 1998            |\r\n+------+----------------+-----------------+\r\n2 rows in set (0.00 sec)\r\n\r\nmysql> select concat(name,\"|\",house_location) from houses;\/*\u5408\u5e76\u5b57\u6bb5\u8f93\u51fa*\/\r\n+---------------------------------+\r\n| concat(name,\"|\",house_location) |\r\n+---------------------------------+\r\n| \u7532|\u5929\u6cb3                         |\r\n| \u7532|\u5929\u6cb3                         |\r\n+---------------------------------+\r\n2 rows in set (0.00 sec)<\/code><\/pre>\n\n\n\n
INSERT INTO\u8bed\u6cd5\uff1a<\/p>\n\n\n\n
INSERT INTO table_name (\u52171, \u52172,...) VALUES (\u503c1, \u503c2,....)<\/code><\/pre>\n\n\n\n
CREATE VIEW\u8bed\u6cd5\uff1a<\/p>\n\n\n\n
CREATE VIEW <\u89c6\u56fe\u540d> AS <SELECT\u8bed\u53e5><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
Data Query Language \u57fa\u672c\u7ed3\u6784\u662f\u7531 select<\u5b57\u6bb5>from<\u8868\u6216\u89c6\u56fe>wh… <\/p>\n
Read the full article<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[8,9],"class_list":["post-87","post","type-post","status-publish","format-standard","hentry","category-mysql","tag-dql","tag-9"],"_links":{"self":[{"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/posts\/87","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/comments?post=87"}],"version-history":[{"count":1,"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/posts\/87\/revisions"}],"predecessor-version":[{"id":88,"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/posts\/87\/revisions\/88"}],"wp:attachment":[{"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/media?parent=87"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/categories?post=87"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jiachen.de.cool\/blog\/wp-json\/wp\/v2\/tags?post=87"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}