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2025-01-16 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Database >
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Shulou(Shulou.com)06/01 Report--
-- create a database
-- create a classroom database
Create database database name default character set character encoding collate collation
Eg:
Create database classroom default character set utf8 collate utf8_general_ci
-- View all databases
Show databases
-- Select a database
Use database name
Eg:
Use classroom
-- delete the database
Drop database database name
Eg:
Drop database classroom
-- create a table
-- create a class table
Create table table name (field name data type [length] attribute [non-null default value increment primary key comment]) charset=utf8,engine=innodb
Eg:
Create table class (
Id int (11) not null auto_increment primary key comment 'student number'
Name varchar (20) not null comment 'name'
Sex varchar (2) not null comment 'gender'
Age int (3) not null comment 'age'
Address varchar (255) not null comment 'Chongqing'
);
-modify the table
-- add field
Alter table table name add field name data type attribute
Eg:
Alter table class add stu_name varchar (255) null
Alter table class add birthday timest-time date
-- modify fields
Alter table Table name change Field New Field Type (Parameter) property
Eg:
Alter table class change stuname name varchar (20) not null
-- deleting a field
Alter table table name drop field
Eg:
Alter table class drop name
-- add primary key
Alter table table name add primary key (field)
Eg:
Alter table class add primary key (id)
-- modify the table name
Alter table table name rename to new name
Eg:
Alter table class rename to class_one
-- copy the table
Method 1: keys cannot be copied
Create table new table select * from old table
Eg:
Create table class1 select * from class
Method 2: full table assignment
Create table new table like old table
Eg:
Create table class1 like class
-- delete the table
-- deleting a single table
Drop table table name
Eg:
Drop table class1
-- Delete multiple tables
Drop table table name 1, table name 2. Table name n
Drop table class,class1,class2
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