数据库常见操作

创建表

CREATE TABLE table_name
(
column_name1 data_type,
column_name2 data_type
);

CREATE TABLE Persons
(
    Id_P int,
    LastName varchar(255),
    FirstName varchar(255),
    Address varchar(255),
    City varchar(255)
);

删除表

DROP TABLE table_name;

 DROP TABLE Person;  

更改表

ALTER TABLE语句用于在已有的表中增加，删除，更改列。

增加列

ALTER TABLE table_name ADD column_name data_type;

ALTER TABLE Person ADD Age int;  
ALTER TABLE Person ADD Name varchar(128);

删除列

ALTER TABLE table_name DROP COLUMN column_name;

ALTER TABLE Person DROP COLUMN Age;  
ALTER TABLE Person DROP COLUMN Name;

更改列

ALTER TABLE table_name ALTER COLUMN column_name data_type;

ALTER TABLE Person ALTER COLUMN ID varchar(16);  
ALTER TABLE Person ALTER COLUMN Name varchar(56);

原文：https://www.cnblogs.com/faithlocus/p/13433688.html