这个sql语句如何实现

显示全部楼层 · 2009-10-9 08:28:00

一个条件不符合的话，换另外一个条件，比如
selectA
from T
where iiii = "ddd"
如果没找到纪录
就换成
selectA
from T
where iiii = "eee"
多谢！

千问 · 2009-10-9 08:28:00

selectA
from T
where iiii = "ddd"oriiii = "eee"

千问 · 2009-10-9 08:28:00

SELECT * FROM t
WHERE t=(SELECT DECODE(COUNT(1),0,'eee','ddd' FROM awhere t='ddd')

千问 · 2009-10-9 08:28:00

SQL> desc test;
名称
是否为空? 类型
----------------------------------------- -------- ----------------------------
A
DATE
B
NUMBER(38)
SQL>select * from test where b=(select case count(*) when 0 then '2'else '1' end from test where b='1');
A
B
---------- ----------

1
SQL> delete from test where b=1;
已删除 1 行。
SQL> commit;
提交完成。
SQL>select * from test where b=(select case count(*) when 0 then '2'else '1' end from test where b='1');
A
B
---------- ----------
02-1月 -08
2
SQL>

千问 · 2009-10-9 08:28:00

成功，多谢楼上各位