SQL Server 12 general operations on tables

01.

Create

CREATE TABLE Strings (ID int);
Go

02.

Add columns to a table

ALTER TABLE Strings
Add String nvarchar (32);
Go

03.

Adding calculated columns

ALTER TABLE Strings
Add ID2 as (id+1);
Go---See there's no need to specify type here.

04.

Modify Definition

ALTER TABLE Strings
ALTER column ID int NOT null;
Go---Drop and add for computed columns first

05.

Delete Column

ALTER TABLE Strings
Drop column ID2;
Go---Delete when you want to add column do not column because according to the added content can see what is added.

06.

Add a primary key to a table

ALTER TABLE Strings
Add constraint pk_id primary key (ID);
Go

07.

Add foreign key to table

ALTER TABLE Strings
Add Constraint Fk_a
Foreign KEY (String) references T (S);
Go---CREATE table T (S nvarchar (+) NOT null primary key);

ALTER TABLE Strings
Add Constraint Fk_a
Foreign KEY (String) references T (S) on the DELETE cascade on UPDATE cascade;
Go---No action, cascade,set null,set default

08, for the table plus uniqu constraints

ALTER TABLE Strings
Add constraint unique_a unique (String);
Go

09.

To add a check constraint to a table

ALTER TABLE Strings
Add Constraint Ck_a
Check (String! = ' 007 ');
Go

10.

Add a DEFAULT constraint to a table

ALTER TABLE Strings
Add Constraint df_a
Default ' 1234656 ' for String;
Go

11.

disabling constraints

ALTER TABLE Strings
Nocheck constraint fk_a;
Go

ALTER TABLE Strings

Nocheck constraint all; ---Disable all constraints

ALTER TABLE Strings

Check constraint all; ---enable all constraints

12.

Delete Constraint

ALTER TABLE Strings
Drop constraint fk_a;
Go

SQL Server 12 general operations on tables