sql判断表名与字段名是否存在语句

if((select count(*) from syscolumns where name = '字段名' and id=(select id from sysobjects where name='表名'))=0)
begin

end

if exists (select * from sysobjects where id = OBJECT_ID('表名') and OBJECTPROPERTY(id, 'IsUserTable') = 1)
DROP TABLE 表名