如何对左外连接得到的null值给一个默认值

[jjstar]

在做左外连接的时候，某些没有匹配的项会产生null数据，我想把sql语句改一下，使得null都有某个默认值，比如下面例子
表t1
列 pk sys_pk
p1 <NULL>
p2 002
p3 003

表t2
列 sys_pk sys_name
001 n1
002 n2
003 n3

外连接语句如下：
SELECT t1.pk, t1.sys_pk, t2.sys_name
FROM t1 LEFT OUTER JOIN
t2 ON t1.sys_pk = t2.sys_pk
得到结果是
pk sys_pk sys_name
p1 <NULL> <NULL>
p2 002 n2
p3 003 n3

而我想要的结果却是
pk sys_pk sys_name
p1 999 999
p2 002 n2
p3 003 n3


不知道说明白了没有

[cui26]

isnull(sys_pk,999)

[sdhdy]

SELECT t1.pk, isnull(t1.sys_pk,'999'), isnull(t2.sys_name,'999')
FROM t1 LEFT OUTER JOIN
t2 ON t1.sys_pk = t2.sys_pk

[lsxaa]

SELECT t1.pk,isnull(t1.sys_pk,999), isnull(t2.sys_name,999)
FROM t1 LEFT OUTER JOIN
t2 ON t1.sys_pk = t2.sys_pk

[sdhdy]

SELECT t1.pk, isnull(t1.sys_pk,'999'), isnull(t2.sys_name,'999')
FROM t1 LEFT OUTER JOIN
t2 ON t1.sys_pk = t2.sys_pk

[lsxaa]

SELECT t1.pk,isnull(t1.sys_pk,'999'), isnull(t2.sys_name,'999')
FROM t1 LEFT OUTER JOIN
t2 ON t1.sys_pk = t2.sys_pk

[deodarsydn]

SELECT t1.pk, isnull(t1.sys_pk,'999'), isnull(t2.sys_name,'999')
FROM t1 LEFT OUTER JOIN
t2 ON t1.sys_pk = t2.sys_pk

[amdwinter]

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[amdwinter]

§§

[lsxaa]

楼上玩啥呢