MySQL Common query

Database

1. Query the size of all data: data_length: Data size index_length: Index size

SELECT concat (Round (sum (data_length+index_length)/1024/1024,2), ' MB ') as DATA from INFORMATION_SCHEMA. Tables\g

2. View the size of the specified database, such as the size of the database Zabbix:

SELECT concat (Round (sum (data_length+index_length)/1024/1024,2), ' MB ') as DATA from INFORMATION_SCHEMA. TABLES where table_schema= ' Zabbix ' \g

　　

3. View the size of a table in the specified database, such as viewing the size of the history table in the database Zabbix

SELECT concat (Round (sum (data_length+index_length)/1024/1024,2), ' MB ') as DATA from INFORMATION_SCHEMA. TABLES where table_schema= ' Zabbix ' and table_name= ' History_uint ' \g

　　

4. View all information related to the specified table

SELECT * FROM INFORMATION_SCHEMA. TABLES where table_schema= ' Zabbix ' and table_name= ' history ' \g

Table

1. Query the first line of records:

SELECT * from table limit 1;

2. Query the first n rows of records

SELECT * from table limit 10;

Or

SELECT * FROM table limit 0, 10;

　　

MySQL Common query