Mysql

1. 查看所有表表名和备注

SELECT TABLE_NAME,
       table_comment
FROM `information_schema`.tables
WHERE table_schema='数据库名'

2. 查询某张表的字段和备注

select column_name,
column_comment 
from information_schema.columns 
where table_name ='表名'
and table_schema='数据库名'

4. 查看所有字段名称和备注

SELECT a.table_name,
       a.column_name,
       a.column_comment
FROM information_schema.columns a,
     `information_schema`.tables b
WHERE a.table_name = b.table_name
  AND a.table_schema = b.table_schema
  AND a.table_schema='数据库名'
ORDER BY a.table_name,
         a.ordinal_position;

5. 处理死锁问题

SELECT * FROM INFORMATION_SCHEMA.INNODB_LOCK_WAITS; 
SHOW OPEN TABLES WHERE In_use > 0;  //查询死锁
SELECT * FROM information_schema.INNODB_TRX; //查询死锁id
kill 33614 //杀死

show processlist;

SHOW ENGINE INNODB STATUS; //查询最近一次的死锁日志