MySQL高级

事务,视图,存储过程,存储函数,触发器,分区


事务:

 事务是一组原子性的查询语言,也就是说,在一组操作中,要么全部执行,要么一个也不执行,如果任何操作失败,则所有操作都失效,保证数据的完整性。
 首先数据库的存储引擎不能是MyISAM,因为MyISAM不支持事务。支持事务的存储引擎有InnoDB,NDB和BDB
查看MySQL支持的存储引擎的命令:
show engines
修改表引擎:
alter table demo engine= innodb

//创建银行表
create table bank(bid int,name char(20),money decimal(6,2));
insert into bank (bid,name,money) values (1,'小米',1000),(2,'小明',1000);
//1.开启事务
begin;
//2.关闭自动提交
set autocommit=0;
//3. 执行操作
select * from bank;
+------+-----------+---------+
| bid  | name      | money   |
+------+-----------+---------+
|    1 | 小米     |  900.00 |
|    2 | 小明      | 1100.00 |
+------+-----------+---------+
update bank set money=money-100 where bid=1;
update bank set money=money+100 where bid=2;
// 4.如果没有问题,那么就确认,如果有问题,那么就rollback
commit;

在PHP中的使用:

try {
  $pdo = new pdo('mysql:host=127.0.0.1;dbname=abc','root','');
  //设置下面的语句都为异常错误,这样才能被try catch接收
  $pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
  $pdo->query("SET NAMES UTF8");
  //1.开启事务
  $pdo->query("BEGIN");
  //2.关闭自动提交
  $pdo->query("SET AUTOCOMMIT=0");
  //3.执行操作
  //bid为1的用户减去100
  $pdo->exec("UPDATE bank SET money=money-100 WHERE bid=1");
  //bid为2的用户加100
  $pdo->exec("UPDATE bank SET money=money+100 WHERE bid=2");
  //4.确认了
  $pdo->exec('COMMIT');

} catch (PDOException $e) {
  //回滚
  $pdo->exec('ROLLBACK');
  echo $e->getMessage();
}

视图

视图是一张虚表,是一组查询记录。
将部分表字段分配到视图中,重要字段不分配,提高数据库安全性。

MySQL高级_第1张图片
Navicat for MySQL中的视图表

示例:
创建一张学生信息表:

mysql> create table stu(id tinyint primary key auto_increment not null,name char(10) not null default '',sex tinyint(1) not null default 0,birthday date);//创建学生信息表
Query OK, 0 rows affected (0.55 sec)
mysql> show tables;//显示当前数据库内的所有表
+---------------+
| Tables_in_stu |
+---------------+
| stu           |
+---------------+
1 row in set (0.00 sec)

mysql> desc stu;//查看stu表的结构
+----------+------------+------+-----+---------+----------------+
| Field    | Type       | Null | Key | Default | Extra          |
+----------+------------+------+-----+---------+----------------+
| id       | tinyint(4) | NO   | PRI | NULL    | auto_increment |
| name     | char(10)   | NO   |     |         |                |
| sex      | tinyint(1) | NO   |     | 0       |                |
| birthday | date       | YES  |     | NULL    |                |
+----------+------------+------+-----+---------+----------------+
4 rows in set (0.01 sec)

mysql> insert into stu(name,sex,birthday)value('Lucy',0,19900101);//往stu表里插入1条数据
Query OK, 1 row affected (0.11 sec)

mysql> select*from stu;//查看表数据
+----+------+-----+------------+
| id | name | sex | birthday   |
+----+------+-----+------------+
|  1 | Lucy |   0 | 1990-01-01 |
+----+------+-----+------------+
1 row in set (0.00 sec)

mysql> insert into stu(name,sex,birthday)value('LiLy',0,19900110),('李雷',1,19910306),('韩梅梅',0,19921112);//再次插入3条数据
Query OK, 3 rows affected (0.12 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> select*from stu;//查看表数据
+----+--------+-----+------------+
| id | name   | sex | birthday   |
+----+--------+-----+------------+
|  1 | Lucy   |   0 | 1990-01-01 |
|  2 | LiLy   |   0 | 1990-01-10 |
|  3 | 李雷   |   1 | 1991-03-06 |
|  4 | 韩梅梅 |   0 | 1992-11-12 |
+----+--------+-----+------------+
4 rows in set (0.06 sec)
mysql> show table status where comment='VIEW';//查看视图
Empty set (0.00 sec)//为空,表示当前数据库没有视图

mysql> create view stuview as select name,sex from stu;//创建视图
Query OK, 0 rows affected (0.11 sec)
mysql> show table status where comment='VIEW'\G//再次查看视图
*************************** 1. row ***************************
           Name: stuview
         Engine: NULL
        Version: NULL
     Row_format: NULL
           Rows: NULL
 Avg_row_length: NULL
    Data_length: NULL
Max_data_length: NULL
   Index_length: NULL
      Data_free: NULL
 Auto_increment: NULL
    Create_time: NULL
    Update_time: NULL
     Check_time: NULL
      Collation: NULL
       Checksum: NULL
 Create_options: NULL
        Comment: VIEW
1 row in set (0.00 sec)
mysql> select * from stuview;//查看视图表数据
+--------+-----+
| name   | sex |
+--------+-----+
| Lucy   |   0 |
| LiLy   |   0 |
| 李雷   |   1 |
| 韩梅梅 |   0 |
+--------+-----+
4 rows in set (0.00 sec)

mysql> alter view stuview as select id,name,sex from stu;//修改视图
Query OK, 0 rows affected (0.08 sec)

mysql> select * from stuview;//再次查看视图表数据
+----+--------+-----+
| id | name   | sex |
+----+--------+-----+
|  1 | Lucy   |   0 |
|  2 | LiLy   |   0 |
|  3 | 李雷   |   1 |
|  4 | 韩梅梅 |   0 |
+----+--------+-----+
4 rows in set (0.00 sec)

mysql> drop view stuview;//删除视图
Query OK, 0 rows affected (0.00 sec)

分区:

查看MySQL插件有无partition,这是实现分区的基本条件:
show plugins;


拓展阅读:
MySQL表的四种分区类型
Mysql 分区 分表相关总结之方案选择
mysql 导出表结构和表数据 mysqldump用法

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