mysql的常用操作和修改，会一直补充（参考官方）

1.创建表结构

CREATE TABLE table_name (column_name column_type)

2.删除数据表

DROP TABLE table_name 

3.插入数据

INSERT INTO table_name ( field1, field2,...fieldN ) VALUES ( value1, value2,...valueN )

 4.查询数据

SELECT column_name,column_name FROM table_name [WHERE Clause] [LIMIT N] [ OFFSET M]

5.where条件

SELECT field1, field2,...fieldN FROM table_name1, table_name2... [WHERE condition1 [AND [OR]] condition2.....

6.update更新数据

UPDATE table_name SET field1=new-value1, field2=new-value2 [WHERE Clause]

7. delete删除数据

DELETE FROM table_name [WHERE Clause]

8.like子句

SELECT field1, field2,...fieldN FROM table_name WHERE field1 LIKE condition1 [AND [OR]] filed2 = 'somevalue'

8.union 语句

SELECT expression1, expression2, ... expression_n FROM tables 
[WHERE conditions] UNION [ALL | DISTINCT] SELECT expression1, expression2, ... expression_n
FROM tables [WHERE conditions]

 9.排序

SELECT field1, field2,...fieldN FROM table_name1, table_name2...
ORDER BY field1 [ASC [DESC][默认 ASC]], [field2...] [ASC [DESC][默认 ASC]]

10.分组

SELECT column_name, function(column_name) FROM table_name WHERE column_name operator value
GROUP BY column_name

11.连接

• INNER JOIN（内连接,或等值连接）：获取两个表中字段匹配关系的记录。
• LEFT JOIN（左连接）：获取左表所有记录，即使右表没有对应匹配的记录。
• RIGHT JOIN（右连接）： 与 LEFT JOIN 相反，用于获取右表所有记录，即使左表没有对应匹配的记录。

SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a INNER JOIN tcount_tbl b ON a.runoob_author = b.runoob_author

SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a LEFT JOIN tcount_tbl b ON a.runoob_author = b.runoob_author

SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a RIGHT JOIN tcount_tbl b ON a.runoob_author = b.runoob_author

12.null值处理

select * , columnName1+ifnull(columnName2,0) from tableName

13.正则

查找name字段中以'st'为开头的所有数据
SELECT name FROM person_tbl WHERE name REGEXP '^st'

14 限制只取第一个，类似于top 1

SELECT * FROM
(
    SELECT paused_time as end_time FROM production_time WHERE created_time = curdate()
    UNION 
    SELECT resumed_time as end_time FROM  pause_timer WHERE created_time = curdate()
    UNION
    SELECT end_time as end_time FROM  timer_idle WHERE created_time = curdate()
) as end_time
ORDER BY end_time DESC 
LIMIT 1