软件测试学习 之 MySQL 视图、事务和索引

视图

-- 创建视图
create view v_student AS
select name 姓名,age 年龄 from student;

-- 查询视图
select * from v_student;

结果：
姓名	年龄
诸葛亮	20
甄宓	18

事务

手动执行事务（一步一步执行，正常最后执行commit，遇到异常执行rollback；

-- 正常情况
begin;
update account set account=account-100 where name='大乔';
update account set account=account+100 where name='小乔';
commit;

-- 另一种写法
start transaction;
update account set account=account-100 where name='大乔';
update account set account=account+100 where name='小乔';
commit;

select * from account;

-- 异常情况（账户余额不能为负数）
begin;
update account set account=account-100 where name='大乔';
update account set account=account+100 where name='小乔';
-- insert 语句 into可以省略
insert account(name,account) VALUES('孙尚香',-1000);
ROLLBACK;

select * from account;

索引

 创建索引

-- 创建表时同时添加索引（三种方式）
drop table if exists test_index;
create table test_index(
id int UNSIGNED PRIMARY key,
name VARCHAR(10) unique,
age int,
key(age)
);

-- 查看索引
show index from test_index;

结果：
Table	    Non_unique	    Key_name	Seq_in_index	Column_name	...
test_index	0	    PRIMARY	    1	            id	        ...
test_index	0	    name	    1	            name        ...
test_index	1	    age	            1	            age        ...   

-- 存储过程批量插入数据
drop procedure if EXISTS batch_insert;
create procedure batch_insert()
BEGIN
    DECLARE maxNum int default 100000;
    declare startNum int DEFAULT 0;
    while startNum < maxNum DO
        INSERT into test(id,topic) values(startNum+1,CONCAT('标题',startNum+1));
        set startNum = startNum + 1;
    end while;
end;

-- 清空表中数据
delete from test;

-- 调用存储过程插入数据
call batch_insert();

-- 开启运行时间监测（设置为0不再监测，重新登录后重置）
set profiling=1;

-- 查询（添加索引之前）
select * from test where topic='标题10001';
show profiles;

-- 添加索引
alter table test drop index index_topic;
-- 或者
drop index index_topic on test;
-- varchar类型长度要与字段长度一致
create index index_topic on test(topic(30));

-- 查看索引
show index from test;

-- 查询（添加索引之后，要用不同的查询条件，同样的查询条件数据库有优化查询的机制）
select * from test where topic='标题10002';
show profiles;

结果：
+----------+------------+--------------------------------------------+
| Query_ID | Duration   | Query                                      |
+----------+------------+--------------------------------------------+
|       .. | ..         | ..                                         |
|       19 | 0.23813500 | select * from test where topic='????10001' |
|       20 | 1.04702000 | create index index_id on test(topic(30))   |
|       21 | 0.13929950 | select * from test where topic='????10002' |
|       22 | 0.00035150 | select * from test where topic='????10002' |
|       23 | 0.00089025 | select * from test where topic='????10005' |
|       24 | 0.01446350 | select * from test where topic='????10099' |
+----------+------------+--------------------------------------------+