SQL Server ALTER statement

1: Add a field to the table

Alter table [table name] add [column name] Type

2: Delete Field

Alter table [table name] Drop column [column name]

3: Modify the field type in the table (you can modify the type of the column, whether it is empty)

ALTER TABLE [table name] ALTER COLUMN [column name] Type

4: Add primary key

Alter table [table name] add constraint [constraint name] primary KEY ([column name])

5: Add UNIQUE Constraint

Alter table [table name] add constraint [constraint name] Unique ([column name])

6: Add default value for a column in a table

Alter table [table name] add constraint [constraint name] Default (defaults) for [column name]
7: Add constraint

Alter table [table name] add constraint [constraint name] Check (content)

8: Add a FOREIGN KEY constraint

Alter table [table name] add constraint [constraint name] FOREIGN key (column name) Referencese another table name (column name)

9: Delete Constraint

Alter table [table name] drop constraint [constraint name]

10: Renaming a table

exec sp_rename ' [Original table name] ', ' [New table name] '

11: Rename the column name

exec sp_rename ' [table name]. [Column name] ', ' [table name]. [New column Name] '

SQL Server ALTER statement