MySQL语句汇总

一、基础

1.数据库相关命令

a>.创建数据库

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CREATE DATABASE 数据库名

b>.创建数据库并设置默认字符集

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CREATE DATABASE 数据库名 DEFAULT CHARACTER SET utf8;

c>.删除数据库

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DROP DATABASE 数据库名

2.数据表相关命令

a>.删除表

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DROP TABLE 表名;

b>.新建表

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DROP TABLE IF EXISTS 表名;

CREATE TABLE 表名 (

`id` INT NOT NULL AUTO_INCREMENT,

`username` VARCHAR(60) NOT NULL DEFAULT '' COMMENT '登录名',

`password` CHAR(32) NOT NULL DEFAULT '' COMMENT '登录密码',

PRIMARY KEY (`id`), -- 主键

INDEX (`username`) -- 索引

) ENGINE=INNODB DEFAULT CHARSET=utf8 COMMENT='新建表';

c>.修改表名

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ALTER TABLE 表名1 RENAME TO 表名2;

d>.添加列

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ALTER TABLE 表名 ADD COLUMN 列名 列类型（如：VARCHAR(30));

e>.删除列

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ALTER TABLE 表名 DROP COLUMN 列名;

f>.几条简单的sql语句

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选择：SELECT * FROM 表名 WHERE 范围;

插入：INSERT INTO 表名(字段名1,字段名2) VALUES(字段值1,字段值2);

删除：DELETE FROM 表名 WHERE 范围;

更新：UPDATE 表名 SET 字段名=字段值 WHERE 范围;

查找：SELECT * FROM 表名 WHERE 字段名 LIKE ’% 字段值 %’ ;

排序：SELECT * FROM 表名 ORDER BY 字段名1,字段名2 [DESC];

总数：SELECT COUNT AS totalcount FROM 表名;

求和：SELECT SUM(字段值) AS sumvalue FROM 表名;

平均：SELECT AVG(字段名) AS avgvalue FROM 表名;

最大：SELECT MAX(字段名) AS maxvalue FROM 表名;

最小：SELECT MIN(字段名) AS minvalue FROM 表名;

g>.赋予数据库用户权限（每个数据库都创建单独的用户）

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CREATE USER '项目用户'@'localhost' IDENTIFIED BY '项目用户密码';

GRANT ALL PRIVILEGES ON 数据库名称.* TO 项目用户@'localhost' ;

或者

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GRANT ALL PRIVILEGES ON 数据库名称.* TO 用户名@'%' IDENTIFIED BY '用户密码';(用’%'表示从任何地址连接)

h>.添加主键

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ALTER TABLE 表名 ADD PRIMARY KEY(列名);

i>.创建索引

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CREATE INDEX 字段名 ON 表名;

j>.删除索引

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DROP INDEX 字段名;

k>.创建视图

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CREATE VIEW 视图名 AS

SELECT 语句;

l>.删除视图

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DROP VIEW 视图名;

m>.联合查询（这块有很多内容，我这里只提出基本的）
结果集列联合：JOIN ，这里我常用的是LEFT JOIN ，格式如下：

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SELECT a.a, a.b, b.c, b.d FROM a LEFT OUT JOIN b ON a.a = b.c;

结果集行联合：UNION或者UNION ALL，格式如下（注意列的名称和个数一定要一致）：

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SELECT a.a as col1, a.b as col2 from a

UNION ALL

SELECT b.c as col1, b.d as col2 from b;

n>.分组:GROUP BY 一般与count,sum,max,min,avg联合使用

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SELECT SUM(字段名1) FROM 表名 GROUP BY 字段名2;

o>.前10条记录

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SELECT * FROM 表名 LIMIT 0,9;(mysql没有top语法，limit一般常用来分页)

p>.排序（desc降序；asc升序；默认是升序）

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SELECT * FROM 表名 ORDER BY 列名 DESC;

二、进阶

a>.去重，一般常用 DISTINCT

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SELECT DISTINCT * FROM 表名;

SELECT DISTINCT(列名) FROM 表名;

b>.复制表

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CREATE TABLE 表名2 AS

(

SELECT * FROM 表名1

)

c>.查询分析器:在sql前面加上EXPLAIN或者DESC，查看该语句执行情况

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EXPLAIN SELECT * FROM 表名;

三、贴一下做报表时写的一些恶心的sql

1.根据查询条件查询出符合条件的项目编号

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SELECT DISTINCT(xp.Id)

FROM xmgl_finance_plan xfp LEFT JOIN xmgl_project xp ON xfp.proId = xp.Id WHERE 1=1

AND xp.proCategory IN ('ITER973')

AND xp.Id IN(0,1,2);

2.-- 查询项目计划表里对应的所有的预算科目对应的合计金额

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SELECT

t.Pid,

xsb2.subjectName,

SUM(t.planTotalAmount) planTotalAmount,

SUM(t.planCurrentAmount) planCurrentAmount,

SUM(t.total_amount) total_amount,

SUM(t.payedMoney) payedMoney,

SUM(t.finalPayment) finalPayment,

SUM(t.CurYearPayedMoney) CurYearPayedMoney

FROM (SELECT

xsb.Id,

xsb.subjectName,

xsb.Pid,

SUM(xfp.planTotalAmount) planTotalAmount,

SUM(xfp.planCurrentAmount) planCurrentAmount,

SUM(xfp.total_amount) total_amount,

SUM(xfp.payedMoney) payedMoney,

SUM(xfp.finalPayment) finalPayment,

SUM(xfp.CurYearPayedMoney) CurYearPayedMoney

FROM xmgl_subject_budget xsb

LEFT JOIN xmgl_project xp

ON xsb.type = xp.subjectType

LEFT JOIN xmgl_finance_plan xfp

ON xsb.Id = xfp.subjectId

WHERE xp.Id = 1

GROUP BY xfp.subjectId,xsb.Id

ORDER BY xsb.Id) AS t

LEFT JOIN xmgl_subject_budget xsb2

ON t.Pid = xsb2.Id

WHERE t.Pid <> 0

GROUP BY t.Pid;

3.-- 查询各个部门在特定科目下的控制额度及支出信息(优化)

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SELECT DISTINCT(xcs1.dept),xsc.subjectName,xcs2.amount,COALESCE(SUM(xfa.amount),0) payedMoney

,xcs2.amount-SUM(xfa.amount) leftAmount

FROM xmgl_control_subject xcs1

LEFT JOIN xmgl_control_subject xcs2 ON xcs1.dept = xcs2.dept AND xcs2.detailId = 3

LEFT JOIN xmgl_subject_control xsc ON xcs2.detailId = xsc.Id

LEFT JOIN xmgl_finance_activity xfa ON xcs2.dept = xfa.department AND xfa.detailId IN('22','23')

GROUP BY xcs1.dept,xcs1.detailId;

4.类似于QQ空间的消息列表

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-- 赞了我

SELECT tf.id,1 AS typeId,c.avatar AS avatar, c.name,ct.catalog AS catalog, ct.id AS messageId, ct.content AS trendsContent,NULL AS replyContent, tf.create_time AS createTime,tf.read AS isRead

FROM trends_fork tf LEFT JOIN cust_trends ct ON tf.trends_id = ct.id LEFT JOIN customer c ON c.id = tf.customer_id

WHERE tf.master_id = 1

UNION ALL

-- 给我留言

SELECT cb.id,2 AS typeId,c.avatar AS avatar,c.name, 3 AS catalog,cb.id AS messageId,NULL AS trendsContent,cb.content AS replyContent,cb.create_time AS createTime,cb.read AS isRead

FROM cust_board cb LEFT JOIN customer c ON cb.customer_id = c.id WHERE cb.master_id = 1

UNION ALL

-- 评论我的动态

SELECT tr.id,3 AS typeId, c.avatar AS avatar, c.name, ct.catalog AS catalog, ct.id AS messageId, ct.content AS trendsContent, tr.content AS replyContent,tr.create_time AS createTime,tr.read AS isRead

FROM trends_reply tr LEFT JOIN cust_trends ct ON tr.trends_id = ct.id LEFT JOIN customer c ON c.id = tr.customer_id

WHERE tr.master_id = 1

UNION ALL

-- 回复了我评论的消息（包括直接回复我的评论、在我的动态下评论别人的回复）

SELECT tra.id,4 AS typeId,c.avatar AS avatar, c.name, ct.catalog AS catalog, tra.trends_id AS messageId,ct.content AS trendsContent, tra.content AS replyContent, tra.create_time AS createTime,tra.read AS isRead

FROM trends_replyat tra LEFT JOIN trends_reply tr ON tra.reply_id = tr.id LEFT JOIN customer c ON c.id = tra.customer_id LEFT JOIN cust_trends ct ON ct.id = tr.trends_id

WHERE tra.at = 1 OR (tra.master_id = 1 AND tra.customer_id != 1)

UNION ALL

-- 留言板中回复我的消息

SELECT cbr.id,5 AS typeId,c.avatar AS avatar, c.name, 3 AS catalog, cb.id AS messageId,cb.content AS trendsContent,cbr.content AS replyContent, cbr.create_time AS createTime,cbr.read AS isRead

FROM cust_board_reply cbr LEFT JOIN cust_board cb ON cbr.board_id = cb.id LEFT JOIN customer c ON cbr.customer_id = c.id

WHERE (cbr.board_customer_id = 1 AND cbr.customer_id != 1 ) OR (cbr.master_id = 1 AND cbr.customer_id != 1) ORDER BY createTime DESC

LIMIT 2,10