Question

我已经构建了以下在Sybase引擎上正常运行的查询：

select *, 
(select COUNT(*) from myTable where column1 != '' and column2!=column3) as myField1,
(select COUNT(*) from myTable where column1 != '' and column2=column3) as myField2
from 
(select column1,column2,column3,column4,column5 
from myTable 
where column1 != '' and column2 != column3) as SUB_VIRTUAL_TABLE

但是，在Oracle引擎上运行相同的查询会引发以下异常：

ORA-00923: FROM keyword not found where expected

可以请任何人帮忙修复此语法吗？非常感谢。 P.s。：表和列存在，当引擎是Sybase时，查询确实运行正常。

预期结果如下：

column1 | column2 | column3 | column4 | column5 | myField 1 | myField2
-----------------------------------------------------------------------
A         B         C         D         E         12          15 
E         F         G         H         I         12          15          
...

Answer 1

您不使用Oracle中的as关键字来对子查询进行别名。您只需指定别名即可。您可能需要在*

中为select添加别名

select sub_virtual_table.*, 
       (select COUNT(*) 
          from myTable 
         where column1 != '' 
           and column2!=column3) as myField1,
       (select COUNT(*) 
          from myTable 
         where column1 != '' 
           and column2=column3) as myField2
  from (select column1,column2,column3,column4,column5 
          from myTable 
         where column1 != '' 
           and column2 != column3) SUB_VIRTUAL_TABLE

由于Oracle中的varchar2列永远不能等于或等于空字符串，因此四个column1谓词没有做任何事情。您可能希望删除它们或执行正确的IS NULL / IS NOT NULL检查。请参阅why Oracle treats the empty string as NULL上的讨论。

Answer 2

在Oracle中，''被视为null，因此条件!= ''可以像is not null一样编写。

试试这个：

select SUB_VIRTUAL_TABLE.*, 
(select COUNT(*) from myTable where column1 is not null and column2!=column3) as myField1,
(select COUNT(*) from myTable where column1 is not null and column2=column3) as myField2
from (
    select column1,column2,column3,column4,column5 
    from myTable 
    where column1 is not null and column2 != column3
) SUB_VIRTUAL_TABLE

获取＆＃34; ORA-00923：找不到FROM关键字＆＃34;在Sybase工作查询中

2 个答案: