DDL language, data definition language
Create database, create data table, modify table structure, delete table. . .create database
create database if not exists database name default charset utf8 collate utf8_general_ci;Create data table
create table if not exists table name (field name field type constraint default value,
field name field type....
);
Modify table
alter table xxx (add, modify, change, drop, rename to)alter table table name add(field name field type, field name field type); add column
alter table table name modify field name field type; modify type
alter table table name change original field name new name field type; modify column name
alter table table name drop field name;
alter table table name rename to new name;
rename table table name to new name;
delete table
drop table if exists 表名;drop database exists database name;
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DML language: data manipulation language ---> data in the data table
Add, delete, modify and insert data:
default insert
insert into table name(field name, field name, field name...) values(v1,v2,v3...)
full column insert
insert into 表名 values (v1,v2,v3...)
Insert multiple lines
insert into table name(field name, field name, field name...) values(v1,v2,v3...),(v1,v2,v3...),(v1,v2,v3...)
delete:
update tablename set field=new value, field=new value. . [where modify conditions]
Revise:
update tablename set field=new value, field=new value. . [where modify conditions]
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DQL language, data query language
Query:show databases; query database
use data name:
show tables;
select version();
select now();
desc table name;//describe
show create table table name;