SQL語句分類: a.DDL 數據定義語言 create drop alter b.DML 數據操作語言 select insert update delete b.DCL 數據控制語言 grant revoke c.TCL 事務控制語言 transaction(begin) commit rollback 創建一個庫: mysql> create database dba; 進入數據: mysql> use dba; 創建一張表: create table user(id int not null auto_increment, name varchar(8), birthday datetime, constraint pk__person primary key(id)); 查看錶結構: mysql> desc user; +----------+------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(8) | YES | | NULL | | | birthday | datetime | YES | | NULL | | +----------+------------+------+-----+---------+----------------+ 3 rows in set (0.01 sec) 插入語句: mysql> insert into user(id,name,birthday) values(1,'lisi','1991-04-26'); Query OK, 1 row affected (0.01 sec) 查詢表內容: mysql> select * from user; +----+------+---------------------+ | id | name | birthday | +----+------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | +----+------+---------------------+ 1 row in set (0.00 sec) AUTO_INCREMENT說明: (1)如果把一個NULL插入到一個AUTO_INCREMENT數據列裏去,MySQL將自動生成下一個序列編號。編號從1開始,並1爲基數遞增。 (2)把0插入AUTO_INCREMENT數據列的效果與插入NULL值一樣。但不建議這樣做,還是以插入NULL值爲好。 (3)當插入記錄時,沒有爲AUTO_INCREMENT明確指定值,則等同插入NULL值。 (4)當插入記錄時,如果爲AUTO_INCREMENT數據列明確指定了一個數值,則會出現兩種情況,情況一,如果插入的值與已有的編號重複,則會出現出錯信息,因爲AUTO_INCREMENT數據列的值必須是唯一的;情況二,如果插入的值大於已編號的值,則會把該數據插入到數據列中,並使在下一個編號將從這個新值開始遞增。也就是說,可以跳過一些編號。 (5)如果用UPDATE命令更新自增列,如果列值與已有的值重複,則會出錯。如果大於已有值,則下一個編號從該值開始遞增。 創建表的語句(id int not null auto_increment)。 mysql> insert into user(id,name,birthday) values(null,'zhangsan','1992-04-26'); Query OK, 1 row affected (0.02 sec) mysql> select * from user; +----+----------+---------------------+ | id | name | birthday | +----+----------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | zhangsan | 1992-04-26 00:00:00 | +----+----------+---------------------+ 2 rows in set (0.00 sec) 如果省去id這一列,insert數據發現也是成功的. mysql> insert into user(name,birthday) values('wangwu','1993-07-26'); Query OK, 1 row affected (0.02 sec) mysql> select * from user; +----+----------+---------------------+ | id | name | birthday | +----+----------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | zhangsan | 1992-04-26 00:00:00 | | 3 | wangwu | 1993-07-26 00:00:00 | +----+----------+---------------------+ 3 rows in set (0.00 sec) mysql> desc user; +----------+------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(8) | YES | | NULL | | | birthday | datetime | YES | | NULL | | +----------+------------+------+-----+---------+----------------+ 3 rows in set (0.00 sec) 注意:插入數據時,數字可以不加單引號(''),但字符串必須加單引號(''). _________________________________________________________________________________________________________________ mysql update用法: update語法: update 表名 set 列1=新值,列2=新值 where expr. mysql> select * from user; +----+----------+---------------------+ | id | name | birthday | +----+----------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | zhangsan | 1992-04-26 00:00:00 | | 3 | wangwu | 1993-07-26 00:00:00 | +----+----------+---------------------+ 3 rows in set (0.00 sec) mysql> update user set birthday = '2018-1-15' where name='zhangsan'; Query OK, 1 row affected (0.02 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from user; +----+----------+---------------------+ | id | name | birthday | +----+----------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | zhangsan | 2018-01-15 00:00:00 | | 3 | wangwu | 1993-07-26 00:00:00 | +----+----------+---------------------+ 3 rows in set (0.00 sec) mysql> update user set name='lucy' where birthday='1993-07-26'; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from user; +----+----------+---------------------+ | id | name | birthday | +----+----------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | zhangsan | 2018-01-15 00:00:00 | | 3 | lucy | 1993-07-26 00:00:00 | +----+----------+---------------------+ 3 rows in set (0.00 sec) update操作多個列的數據時,中間使用逗號','分割開. mysql> update user set name='saluya',birthday='2010-01-11' where id=2; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from user; +----+--------+---------------------+ | id | name | birthday | +----+--------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | saluya | 2010-01-11 00:00:00 | | 3 | lucy | 1993-07-26 00:00:00 | +----+--------+---------------------+ 3 rows in set (0.00 sec) 當update操作並沒有匹配到where條件時,update操作不會報錯. mysql> update user set birthday='1991-06-25' where name='wangtian'; Query OK, 0 rows affected (0.00 sec) Rows matched: 0 Changed: 0 Warnings: 0 mysql> select * from user; +----+----------+---------------------+ | id | name | birthday | +----+----------+---------------------+ | 1 | lisi | 1991-04-26 00:00:00 | | 2 | zhangsan | 2018-01-15 00:00:00 | | 3 | wangwu | 1993-07-26 00:00:00 | +----+----------+---------------------+ 3 rows in set (0.00 sec)
mysql數據庫insert和update操作
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