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mySql study notes: easier than writing sql server

黄舟
Release: 2017-02-15 11:05:12
Original
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在学mySql。总的感觉,mySql与Sql Server差不多,语法都很象,但mySql也许是吸取了SQL SERVER的一些经验,SQL语句书写起来更加简单。

比如说,设置主键、索引,SQL SERVER里的语句我是记不住的,但mysql却很简便:



CREATE table t(
id int not null
,name varchar(50) null
,primary key(id)
,index ix_name(name));
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又如:


use test;

drop table if exists t3;
CREATE TABLE t3 (
  id INT NOT NULL,
  NAME CHAR(30) NOT NULL,
  age INT NOT NULL,
  info VARCHAR (255),
  INDEX MultiIdx(id, NAME, age)
);


INSERT INTO t3(id ,NAME,age,info) VALUES(1,'小明',12,'nihao'),(2,'小芳',16,'nihao');

explain select * from t3 where name='小芳';
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如果存在某表,先删再建之;

显示执行情况,看看复合索引是否被用,太简便了。


mysql 的查询还支持正则表达式


另外,mysql的表支持两种类型:innoDB 和 myISAM。后者不支持事务,但速度更快,很适合用在只读。

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