MySQL操作

基本操作

指定位置添加列

• 添加new_column_name到old_column_name之后(AFTER)

ALTER TABLE tablename ADD COLUMN new_column_name VARCHAR(255) CHARACTER SET UTF8 AFTER old_column_name;

• 添加new_column_name到第一列(FIRST)

ALTER TABLE tablename ADD [COLUMN] new_column_name VARCHAR(255) CHARACTER SET UTF8 FIRST

表修改

• 修改表名

ALTER TABLE table_name RENAME TO new_table_name;

• 修改列名

ALTER TABLE table_name CHANGE old_column_name new_column_name;

• 修改属列属性

ALTER TABLE table_name MODIFY column_name VARCHAR(1500);

视图

• 创建视图(create view ... as ...)

CREATE VIEW view_name AS
SELECT column1, SUM(column2 * column3) sum
FROM  table_name
GROUP by column1
ORDER BY sum DESC;

删除表数据

• 删除指定数据(delete)

DELETE FROM table_name [conditions];

---

• 删除全部数据(truncate, delete)

# 删除全部数据， id重置为0
TRUNCATE table_name;

# 仅删除全部数据
DELETE FROM table_name;

---

• 删除表(drop)

DROP table_name;

插入数据(INSERT)

• 插入数据
  INSERT INTO table_name(field1, field2,... fieldN)
VALUES(value1, value2,... valueN);
• 表间相互插入(INSERT INTO ... SELECT)
  
  • 两张表间相互插入
    INSERT INTO table_name1(field1, field2)
SELECT field1, field2
FROM table_name2;
  • 三张表间相互插入
    INSERT INTO table_name1(field1, field2)
SELECT * FROM
(SELECT table_name2.field1, table_name3.field2
FROM b JOIN c) AS tb

查找(SELECT)

• 查找重复记录
  
  • 查找全部重复记录 重复字段(column_1, column_2, ..., column_n)

SELECT * FROM table_name
WHERE (column_1, column_2, ..., column_n)
IN (
SELECT column1, column2, ..., column_n
FROM table_name
GROUP BY colum_1, column_2, ..., column_n
HAVING COUNT(*) > 1
);

  • 过滤重复记录（只显示一条）
    
SELECT * FROM table_name
WHERE (column_1, column_2, ..., column_n)
IN (
SELECT column1, column2, ..., column_n
FROM table_name
GROUP BY colum_1, column_2, ..., column_n
HAVING COUNT(*) > 1
) AND id
IN (
SELECT MIN(ID) FROM table_name
GROUP BY colum_1, column_2, ..., column_n
HAVING COUNT(*) > 1);

• 删除重复记录只保留id最小记录

select * from vitae a
where
(a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq 
having count(*) > 1)
and rowid not in (select min(rowid) from vitae group
by peopleId,seq having count(*)>1)

数据库导出(mysqldump)

用法: mysqldump -u用户名 -p密码 [-d] 数据库名 [表名] > 脚本名;

• 导出数据库db_name的表结构到db.sql [-d]

mysqldump -uroot -pdbpasswd -d db_name > db.sql;

• 导出数据库db_name中表table_name的结构到 db.sql [-d]

mysqldump -uroot -pdbpasswd -d db_name table_name > db.sql;

• 导出数据库db_name所有表结构及数据到db.sql

mysqldump -uroot -pdbpasswd  db_name > db.sql;

• 导出数据库db_name中表table_name结构及数据到db.sql

mysqldump -uroot -pdbpasswd db_name test > db.sql;