SQL Server Add or modify columns

--Add columns

IF not EXISTS (SELECT * from syscolumns WHERE id=object_id (' tbl_tranwoandcochistorybyrailassure ') and name= ' CreatedDate ' )
BEGIN

ALTER TABLE Tbl_tranwoandcochistorybyrailassure
ADD createddate DATETIME not NULL DEFAULT GETDATE ()

END

--Modify Columns

IF EXISTS (SELECT * from syscolumns WHERE id=object_id (' tbl_tranwoandcochistorybyrailassure ') and Name= ' CreatedDate ')
BEGIN

ALTER TABLE Tbl_tranwoandcochistorybyrailassure
ALTER COLUMN createddate NVARCHAR (10)

END

--1. Deleting a column, deleting the default value constraint name first

IF EXISTS (SELECT * from syscolumns WHERE id=object_id (' tbl_tranwoandcochistorybyrailassure ') and Name= ' CreatedDate ')
BEGIN

ALTER TABLE Tbl_tranwoandcochistorybyrailassure
DROP constraint df__tbl_tranw__createddate__359dcdd0

END

--2. Deleting columns

IF EXISTS (SELECT * from syscolumns WHERE id=object_id (' tbl_tranwoandcochistorybyrailassure ') and Name= ' CreatedDate ')
BEGIN

ALTER TABLE Tbl_tranwoandcochistorybyrailassure
DROP COLUMN CreatedDate

END

SQL Server Add or modify columns