MySQL Common commands

MySQL command on-line Baidu comes out is a lot of, this is just to tidy up more than usual instructions.

Baidu Library In this article can refer to http://wenku.baidu.com/view/b5e83a27ccbff121dd368357.html

Common types of data

The MySQL Terminator is ";" ends.

1. Show the host database

　　show databases;

2. Deleting a database

　　Drop database dbName;

3. Create a Database

　　drop database [if not EXISTS] dbName;

The parentheses section is optional, and the database is determined to be created if it does not exist.

4. Switch, use the specified database

　　Use DbName;

5. Display all table objects currently using the database

　　Show tables;

6. Display the underlying structure describe (DESC)

　　DESC TableName;

Use of 7.ALTER table

Show Table T1 first. Table T1 is created using the following methods:

CREATE TABLE T1 (a integer,b CHAR (10));

Rename the table T1 to T2:

ALTER TABLE T1 RENAME T2;

Change column A from interger to tinyint not NULL (the name remains the same), change column B from char (10) to char (20), and rename column B to column C:

ALTER TABLE T2 MODIFY A TINYINT not NULL, change b C CHAR (20);

Add a new timestamp column with the name D:

ALTER TABLE T2 ADD D TIMESTAMP;

To add an index to column D and column A:

ALTER TABLE T2 Add index (d), add index (a);

Delete Column C:

ALTER TABLE T2 DROP COLUMN C;

Add a new auto_increment integer column with the name C:

ALTER TABLE T2 ADD C INT UNSIGNED not NULL auto_increment,

ADD PRIMARY KEY (c);

Note that we indexed the C (as primary KEY) because the auto_increment column must be indexed. At the same time we define C as not NULL because the primary key column cannot be null

MySQL Common commands