存在的纪录不允许插入

[hljhl]

我的问题是：动态向一个表中追加纪录，如果表中一有这条纪录的gh,则不追加。我是这样写的但运行时不如意。
insert y_txb gh,xm,xb,csdate select gh,xm,xb,csdate from zzryxxb where datediff(year,csdate,getdate())>10 and not exists(select gh from y_txb)
应该怎样写，谢谢

[starwill]

insert y_txb gh,xm,xb,csdate select gh,xm,xb,csdate from zzryxxb where datediff(year,csdate,getdate())>10 and hg not exists(select gh from y_txb)

[starwill]

用条件判断:
if not exists(select * from y_txb where gh = @gh,xm = @xxm...)
begin
insert y_txb gh,xm,xb,csdate select gh,xm,xb,csdate from zzryxxb where datediff(year,csdate,getdate())>10 and not exists(select gh from y_txb)
end

[brightheroes]

insert y_txb gh,xm,xb,csdate select gh,xm,xb,csdate from zzryxxb where datediff(year,csdate,getdate())>10 and gh not in (select gh from y_txb)