加入多个sql语句
问题描述:
SELECT column_a1,column_b1,column_c1,column_d1,column_e1,column_f1,column_g1
FROM mytable WHERE id=12 AND detectcolumn=1
UNION ALL
SELECT column_a2,column_b2,column_c2,column_d2,column_e2,column_f2
FROM mytable WHERE id=12 AND detectcolumn=2
UNION ALL
SELECT column_a3,column_b3,column_c3,column_d3,column_e3,column_f3,column_g3
FROM mytable WHERE id=12 AND detectcolumn=3
UNION ALL
SELECT column_a4 from mytable WHERE id=12 AND detectcolumn=4
UNION ALL
SELECT column_a5 from mytable WHERE id=12 AND detectcolumn=5
UNION ALL
SELECT column_a6 from mytable WHERE id=12 AND detectcolumn=6
UNION ALL
SELECT column_a7 from mytable WHERE id=12 AND detectcolumn=7
我应该如何将所有这些sql语句合并成一个单独的sql语句。我想根据detectcolumn的值从mytable中获取特定的列。加入多个sql语句
我试着使用UNION ALL,但它给错误ORA-01789:查询块有结果列的数目不正确
答
使用模式,如:
select
case detectcolumn
when 4 then column_a4
when 5 then column_a5
when 6 then column_a6
end
from
my_table
where
id = 12 and
detectcolumn in (4,5,6)
每个联盟选择句子必须有相同的字段计数。你的工会不符合这个要求。试着解释你将会得到什么。 – AnatolyS 2013-03-11 10:15:45
我想从** mytable **获取特定列,具体取决于** detectcolumn的值** – Akki 2013-03-11 10:17:18
将此问题放在问题中,而不是作为注释 – 2013-03-11 10:17:37