存储在系统中的数据是数据库管理系统(DBMS)的核心,数据库被设计用来管理数据的存储、访问和维护数据的完整性,MariaDB中提供了功能丰富的数据库管理语句,包括有效地向数据库中插入数据的INSERT语句,更新数据的UPDATE语句以及当数据不再使用时删除数据的DELETE语句,本小结将依次来介绍这些命令的使用方法和技巧.
MariaDB 插入数据
MariaDB中使用INSERT语句插入数据,可以插入的方式有:插入完整记录,插入记录的部分,插入多条记录,插入另一个查询的结果,废话不多说,老样子先来看一下插入语句的写法吧:
INSERT INTO 表名称(字段1,字段2,字段3,.....) VALUES(数值1,数值2,数值3....)
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为了方便后续的练习,我们先来创建一个表结构,SQL语句如下:
MariaDB [lyshark]> create table person
-> (
-> id int unsigned not null auto_increment,
-> name char(50) not null default '',
-> age int not null default 0,
-> info char(50) null,
-> primary key(id)
-> );
Query OK, 0 rows affected (0.00 sec)
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◆在所有字段插入数据◆
在person表中,插入一条新记录id=1,name=LyShark,age=22,info=Lawyer,SQL语句如下:
MariaDB [lyshark]> select * from person;
Empty set (0.00 sec)
MariaDB [lyshark]> insert into person(id,name,age,info) values(1,'LyShark',22,'Lawyer');
Query OK, 1 row affected (0.00 sec)
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
+
1 row in set (0.00 sec)
MariaDB [lyshark]>
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◆在指定字段插入数据◆
在person表中,插入一条新记录,name=Willam,age=18,info=sports,我们不给其指定ID,SQL语句如下:
MariaDB [lyshark]> desc person;
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| Field | Type | Null | Key | Default | Extra |
+
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
| name | char(50) | NO | | | |
| age | int(11) | NO | | 0 | |
| info | char(50) | YES | | NULL | |
+
4 rows in set (0.00 sec)
MariaDB [lyshark]> insert into person(name,age,info) values('Willam',18,'sports man');
Query OK, 1 row affected (0.04 sec)
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
+
2 rows in set (0.00 sec)
MariaDB [lyshark]>
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◆同时为表插入多条记录◆
在person表中,同时插入3条新记录,有多条只需要在每一条的后面加,即可,SQL语句如下:
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
+
2 rows in set (0.00 sec)
MariaDB [lyshark]> insert into person(name,age,info) values('Evans',27,'secretary'),
-> ('Dale',22,'cook'),
-> ('Edison',28,'singer');
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
| 3 | Evans | 27 | secretary |
| 4 | Dale | 22 | cook |
| 5 | Edison | 28 | singer |
+
5 rows in set (0.00 sec)
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◆将查询结果插入到表中◆
为了实现将另一个表中的记录插入到本表中,我们新建一个person_old表,其表结构和person相同,我们将person_old表中的内容全部迁移到person中去,SQL语句如下:
1.创建一个person_old表,并插入测试字段:
MariaDB [lyshark]> create table person_old
-> (
-> id int unsigned not null auto_increment,
-> name char(50) not null default '',
-> age int not null default 0,
-> info char(50) null,
-> primary key(id)
-> );
Query OK, 0 rows affected (0.01 sec)
MariaDB [lyshark]> insert into person_old
-> values(11,'harry',20,'student'),(12,'Beckham',33,'police');
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
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2.接下来我们将person_old表中的内容迁移到person中去
MariaDB [lyshark]> select * from person_old;
+
| id | name | age | info |
+
| 11 | harry | 20 | student |
| 12 | Beckham | 33 | police |
+
2 rows in set (0.00 sec)
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
| 3 | Evans | 27 | secretary |
| 4 | Dale | 22 | cook |
| 5 | Edison | 28 | singer |
+
5 rows in set (0.00 sec)
MariaDB [lyshark]> insert into person(id,name,age,info)
-> select id,name,age,info from person_old;
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
| 3 | Evans | 27 | secretary |
| 4 | Dale | 22 | cook |
| 5 | Edison | 28 | singer |
| 11 | harry | 20 | student |
| 12 | Beckham | 33 | police |
+
7 rows in set (0.00 sec)
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MariaDB 更新数据
表中有数据之后,接下来我们可以对数据进行更新操作,MariaDB中使用UPDATE语句更新表中的记录,可以更新特定的行或同时更新所有的行,基本语句结构如下:
UPDATE 表名称
SET 字段1=修改值,字段2=修改值,字段3=修改值
where (限定条件);
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◆更新表中指定字段◆
修改person表中数据,将id=11的name字段的值改为xxxx,age字段改为200,SQL语句如下:
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
| 3 | Evans | 27 | secretary |
| 4 | Dale | 22 | cook |
| 5 | Edison | 28 | singer |
| 11 | harry | 20 | student |
| 12 | Beckham | 33 | police |
+
7 rows in set (0.00 sec)
MariaDB [lyshark]> update person set age=200,name='xxxx' where id=11; #更新单个字段
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
| 3 | Evans | 27 | secretary |
| 4 | Dale | 22 | cook |
| 5 | Edison | 28 | singer |
| 11 | xxxx | 200 | student |
| 12 | Beckham | 33 | police |
+
7 rows in set (0.00 sec)
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◆更新表的一个范围◆
更新person表中的记录,将1-12的info字段全部改为lyshark blog,SQL语句如下:
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | Lawyer |
| 2 | Willam | 18 | sports man |
| 3 | Evans | 27 | secretary |
| 4 | Dale | 22 | cook |
| 5 | Edison | 28 | singer |
| 11 | xxxx | 200 | student |
| 12 | Beckham | 33 | police |
+
7 rows in set (0.00 sec)
MariaDB [lyshark]> update person set info='lyshark blog' where age between 1 and 200; #指定修改的字段
Query OK, 7 rows affected (0.00 sec)
Rows matched: 7 Changed: 7 Warnings: 0
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | lyshark blog |
| 2 | Willam | 18 | lyshark blog |
| 3 | Evans | 27 | lyshark blog |
| 4 | Dale | 22 | lyshark blog |
| 5 | Edison | 28 | lyshark blog |
| 11 | xxxx | 200 | lyshark blog |
| 12 | Beckham | 33 | lyshark blog |
+
7 rows in set (0.00 sec)
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MariaDB 删除数据
◆删除表中指定记录◆
通过id号,删除表中指定列,此处删除第id=12号,这条记录,SQL语句如下:
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | lyshark blog |
| 2 | Willam | 18 | lyshark blog |
| 3 | Evans | 27 | lyshark blog |
| 4 | Dale | 22 | lyshark blog |
| 5 | Edison | 28 | lyshark blog |
| 11 | xxxx | 200 | lyshark blog |
| 12 | Beckham | 33 | lyshark blog |
+
7 rows in set (0.00 sec)
MariaDB [lyshark]> delete from person where id=12; #通过id号，删除表中指定列
Query OK, 1 row affected (0.05 sec)
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | lyshark blog |
| 2 | Willam | 18 | lyshark blog |
| 3 | Evans | 27 | lyshark blog |
| 4 | Dale | 22 | lyshark blog |
| 5 | Edison | 28 | lyshark blog |
| 11 | xxxx | 200 | lyshark blog |
+
6 rows in set (0.00 sec)
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◆删除表的一个范围◆
在person表中,删除age字段值在19-22的记录,SQL语句如下:
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 1 | LyShark | 22 | lyshark blog |
| 2 | Willam | 18 | lyshark blog |
| 3 | Evans | 27 | lyshark blog |
| 4 | Dale | 22 | lyshark blog |
| 5 | Edison | 28 | lyshark blog |
| 11 | xxxx | 200 | lyshark blog |
+
6 rows in set (0.00 sec)
MariaDB [lyshark]> delete from person where age between 19 and 22; #指定范围删除
Query OK, 2 rows affected (0.00 sec)
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 2 | Willam | 18 | lyshark blog |
| 3 | Evans | 27 | lyshark blog |
| 5 | Edison | 28 | lyshark blog |
| 11 | xxxx | 200 | lyshark blog |
+
4 rows in set (0.00 sec)
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◆清空表中所有记录◆
MariaDB [lyshark]> select * from person;
+
| id | name | age | info |
+
| 2 | Willam | 18 | lyshark blog |
| 3 | Evans | 27 | lyshark blog |
| 5 | Edison | 28 | lyshark blog |
| 11 | xxxx | 200 | lyshark blog |
+
4 rows in set (0.00 sec)
MariaDB [lyshark]> delete from person; #清空表中所有记录
Query OK, 4 rows affected (0.00 sec)
MariaDB [lyshark]> select * from person;
Empty set (0.00 sec)
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