Common commands of database 1

1.Win+R Of MySQL On and off of .

• Enable ：net start mysql
• close ：net stop mysql

2.MySQL Log in and log out of .

• mysql -uroot -p -P3306
• password: password
• sign out ：exit perhaps quit

3. Server version 、 date 、 User display

• Display server version ：SELECT VERSION();
• Show current date ：SELECT NOW();
• Show current user ：SELECT USER();

4. Often look at the database .

• show databases;

5. Create database .

• create database demo1;

6.if not exits The use and error created display .

• First of all, we have created demo1 This library , When we create again demo1 An error will be reported , At this time, we can use if not exits

7. View the encoding format of the database .

• show create database database_name;

8. Change the encoding format of the database when creating the database .

• create database database_name character set gbk;

9. Modify the created database code .

• alter database database_name character set gbk;

10. Delete the created library .

• drop database database_name;

11. About the classification of database languages .

• DDL（ Data definition language ）： Objects used to define the database , Such as data sheet 、 View 、 Index, etc.
• DML（ Data manipulation language ）： Update in database table 、 Add and delete records
• DCL（ Data control language ）： It refers to the statements used to set user permissions and control transactions
• DQL（ Data query language ）(***)： Query of data table records

12. The operation of the table .

• That's ok ： Record
• Column ： Field

13. Enter a library .

• use database_name;

14. Often see which tables exist under the Library .

• show tables;

15. Create table .

• create table table_name1(
• age int unsigned,
• username varchar(20),
• salary float(9.2),
• );

16. View table structure .

• 1：show columns from table_name;
• 2：desc table_name;

17. Insert data into a table .

• 1：insert table_name (col_name1,col_name2,col_name3...) values (col_key1,col_key2,col_key3...);
• 2：insert table_name values (col_key1,col_key2,col_key3...);
• 3：insert table_name (col_name1,col_name2) values (col_key1,col_key2); 

18. Look up the records in the table .

• select * from table_name;

19. Delete table records .

• Delete the record of the specified field ：delete from table_name where col_name=col_key;
• Delete the records of all fields in the table ：delete from table_name;

20. Enable the table to output Chinese , Sometimes we will find that after inserting Chinese data , Use select * from table_name Unable to output Chinese .

• set character_set_results=gb2312;

21. Enable the output records in the table to be aligned .

• charset gbk;