数据库有两个表，求关联SQL

select a.列1,a.列2,a.列3,isnull(b.列2,0),isnull(b.列3,0),isnull(b.列4,0) from a left join b on a.列1=b.列1以上sqlserver写法，oracle的话把isnull替换成nvl，别名自己起吧