Check Column Existence Before Add/Drop in the Table

IF NOT EXISTS(SELECT 1 FROM SYS.OBJECTS O INNER JOIN SYS.COLUMNS C ON O.OBJECT_ID = C.OBJECT_ID WHERE o.NAME ='TableName' AND C.NAME ='ColumnName')
BEGIN
Alter Table dbo.TableName Add ColumnName DataType
END

IF EXISTS(SELECT 1 FROM SYS.OBJECTS O INNER JOIN SYS.COLUMNS C ON O.OBJECT_ID = C.OBJECT_ID WHERE O.NAME ='TableName' AND C.NAME ='ColumnName')
BEGIN
Alter Table dbo.TableName Drop Column 'ColumnName'
END