Some Alter Queries For SQL Server (Tested in SQL Server 2005)

ABOUT WHAT	QUERIES
Adding Primary Key	ALTER TABLE Table_Name ADD PRIMARY KEY (Column_Name)
Adding Foreign Key with Cascade	ALTER TABLE child_name add CONSTRAINT constraint_name FOREIGN KEY (childtable column1, column2, ... column_n) REFERENCES parent_table(column1, column2, ... column_n) on update cascade;
Adding Unique Key	ALTER TABLE Table_Name ADD UNIQUE (Column_Name);
Adding New Column	ALTER TABLE Table_Name ADD NewCol VARCHAR(50);
Altering Column Type/Width	ALTER TABLE Table_Name ALTER COLUMN NewCol varchar(80) NOT NULL;
Addng Identity(Note:Table Should Be Empty)	ALTER TABLE Table_Name ALTER COLUMN ColName ADD CONSTRAINT IDENTITY(1,1);
Adding Default Value	ALTER TABLE Table_Name ADD CONSTRAINT Constraint_Name DEFAULT 'dotnetkanna' FOR Column_Name;
Drop Constraint	ALTER TABLE Table_Name DROP CONSTRAINT Constraint_Name;
Drop Column	ALTER TABLE Table_Name DROP Column Column_Name;
Rename The Table	SP_RENAME 'Old_TableName','New_TableName';
Rename The Column	sp_rename @objname = 'table_name.old_column_name', @newname = 'new_column_name', @objtype = 'COLUMN';
Rename The Database	sp_renamedb 'Old_DBName', 'New_DBName';