-- *************** ELIMINAR COLUMNA
IF EXISTS(SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '[TABLA]' AND  COLUMN_NAME = '[COLUMNA]')
BEGIN
	ALTER TABLE [TABLA] DROP COLUMN [COLUMNA]
END

-- *************** AGREGAR COLUMNA
IF  NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '[TABLA]' AND  COLUMN_NAME = '[COLUMNA]')
BEGIN
	ALTER TABLE [TABLA] ADD [COLUMNA] INT NULL
END