Alter Table Alter Column

CREATE TABLE dbo.Employee

(
EmployeeID INT IDENTITY (1,1) NOT NULL
,FirstName VARCHAR(50) NULL
,MiddleName VARCHAR(50) NULL
,LastName VARCHAR(50) NULL
,DateHired datetime NOT NULL
)

--Change column name
sp_rename 'table name','old column name','column'

-- Change the datatype to support 100 characters and make NOT NULL
ALTER TABLE dbo.Employee
ALTER COLUMN FirstName VARCHAR(100) NOT NULL

-- Change datatype and allow NULLs for DateHired
ALTER TABLE dbo.Employee
ALTER COLUMN DateHired SMALLDATETIME NULL

-- Set SPARSE columns for Middle Name (sql server 2008 only)
ALTER TABLE dbo.Employee
ALTER COLUMN MiddleName VARCHAR(100) SPARSE NULL