mysql 语句笔记

1. 查询某个表中所有非空字段名

SELECT `COLUMN_NAME`
FROM `information_schema`.`COLUMNS`
WHERE
`IS_NULLABLE` = 'No'
AND `TABLE_NAME` = 'feed'
AND `TABLE_SCHEMA` = 'prodb_mgmt'

2.   查看一个表的所有字段

describe <表名>

3.  查看表大小  http://stackoverflow.com/questions/9620198/how-to-get-the-sizes-of-the-tables-of-a-mysql-database 

SELECT 
    table_name AS `Table`, 
    round(((data_length + index_length) / 1024 / 1024), 2) `Size in MB` 
FROM information_schema.TABLES 
WHERE table_schema = "$DB_NAME"
    AND table_name = "$TABLE_NAME";

4. 显示表的建表语句  http://dev.mysql.com/doc/refman/5.7/en/show-create-table.html 

mysql> show create table serverStatusInfo \G;
*************************** 1. row ***************************
       Table: serverStatusInfo
Create Table: CREATE TABLE `serverStatusInfo` (
  `date` date NOT NULL,
  `server` varchar(45) NOT NULL,
  `requestsActiveMax` int(10) unsigned default '0',
  `requestTimeMax` int(10) unsigned default '0',
  `requestTimeMean` float default '0',
  `requestTimeStdDev` float default '0',
  PRIMARY KEY  (`date`,`server`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk
1 row in set (0.00 sec)

 4.  删除表中所有数据 Delete / Truncate

delete from tableName;
Delete: will delete all rows from your table. Next insert will take next auto increment id.

truncate tableName;
Truncate: will also delete the rows from your table but it will start from new row with 1.