Some SQL statements often used in work and study

[Introduction] Some commonly used SQL statements: Create a new table:

CREATE table [表名] ( [自动编号字段] int IDENTITY (1,1) PRIMARY KEY , [字段1] nVarChar(50) default 默认值 null , [字段2] ntext null , [字段3] d

Some commonly used SQL statements:

Create a new table:

create table [表名] ( [自动编号字段] int IDENTITY (1,1) PRIMARY KEY , [字段1] nVarChar(50) default '默认值' null , [字段2] ntext null , [字段3] datetime, [字段4] money null , [字段5] int default 0, [字段6] Decimal (12,4) default 0, [字段7] image null , )

Create a new table:

create table [表名] ( [自动编号字段] int IDENTITY (1,1) PRIMARY KEY , [字段1] nVarChar(50) default '默认值' null , [字段2] ntext null , [字段3] datetime, [字段4] money null , [字段5] int default 0, [字段6] Decimal (12,4) default 0, [字段7] image null , )

Delete table:

Drop table [table name]

Insert data:

INSERT INTO [表名] (字段1,字段2) VALUES (100,'51WINDOWS.NET')

Delete data:

DELETE FROM [表名] WHERE [字段名]>100

Update data:

UPDATE [表名] SET [字段1] = 200,[字段2] = '51WINDOWS.NET' WHERE [字段三] = 'HAIWA'

New field:

ALTER TABLE [表名] ADD [字段名] NVARCHAR (50) NULL

Delete field:

ALTER TABLE [表名] DROP COLUMN [字段名]

Modify field:

ALTER TABLE [表名] ALTER COLUMN [字段名] NVARCHAR (50) NULL

Rename table: (Access renames the table, please refer to the article: Rename the table in the Access database)

sp_rename 'Table name', 'New table name', 'OBJECT '

New constraint:

ALTER TABLE [表名] ADD CONSTRAINT 约束名 CHECK ([约束字段] <= '2000-1-1')

Delete constraint:

ALTER TABLE [表名] DROP CONSTRAINT 约束名

New default Value

ALTER TABLE [表名] ADD CONSTRAINT 默认值名 DEFAULT '51WINDOWS.NET' FOR [字段名]

Delete default value

ALTER TABLE [表名] DROP CONSTRAINT 默认值名

The above is the content of some SQL statements often used in work and study, more For more related content, please pay attention to the PHP Chinese website (m.sbmmt.com)!