Oracle SQL：将当前行和前两行的excel嵌套if条件转换为SQL

Posted 2023-03-24

【中文标题】Oracle SQL：将当前行和前两行的excel嵌套if条件转换为SQL

【英文标题】：Oracle SQL: Convert excel nested if condition on Current row and previous two rows to SQL

【发布时间】：2022-01-05 07:56:57

【问题描述】：

我有一个带有嵌套 IF 条件的 excel 公式，它将当前行值与前一行进行比较，并将前一行与同一列中的前第二行值进行比较。

公式：

=IF(B8<>B7,IF(B7<>B6,B6,B7),B8) 

尝试下面的查询，但得到错误“ORA-00920：无效的关系运算符”

select MYTABLE.*,
CASE    WHEN MSYMBOL over (order by MDATE)   <> lag(MSYMBOL,1) over (order by MDATE)
        THEN CASE 
                        WHEN lag(MSYMBOL,1) over (order by MDATE) <> lag(MSYMBOL,2) over (order by MDATE)
                        THEN lag(MSYMBOL,2) over (order by MDATE)
                        ELSE lag(MSYMBOL,1) over (order by MDATE)
             END,
        ELSE MSYMBOL over (order by MDATE)
END as FLAG
from MYTABLE

表创建、插入语句和查询在此链接DB<>FIDDLE更新。

感谢任何帮助。提前致谢。

谢谢， 里查

【参考方案1】：

MSYMBOL over (order by MDATE) 无效，您只想使用MSYMBOL。 在第一个 END 后面多了一个逗号。 另外，NULL <> something 从来都不是真的，需要说明这一点。

你可以使用：

select MYTABLE.*,
       CASE
       WHEN MSYMBOL <> lag(MSYMBOL,1) over (order by MDATE)
       OR   (MSYMBOL IS NULL AND lag(MSYMBOL,1) over (order by MDATE) IS NOT NULL)
       OR   (MSYMBOL IS NOT NULL AND lag(MSYMBOL,1) over (order by MDATE) IS NULL)
       THEN CASE 
            WHEN lag(MSYMBOL,1) over (order by MDATE) <> lag(MSYMBOL,2) over (order by MDATE)
            OR   (lag(MSYMBOL,1) over (order by MDATE) IS NULL AND lag(MSYMBOL,2) over (order by MDATE) IS NOT NULL)
            OR   (lag(MSYMBOL,1) over (order by MDATE) IS NOT NULL AND lag(MSYMBOL,2) over (order by MDATE) IS NULL)
            THEN lag(MSYMBOL,2) over (order by MDATE)
            ELSE lag(MSYMBOL,1) over (order by MDATE)
            END
       ELSE MSYMBOL
       END as FLAG
from   MYTABLE

但您可能会更好地反转比较以使用=。

select MYTABLE.*,
       CASE
       WHEN MSYMBOL = lag(MSYMBOL,1) over (order by MDATE)
       THEN MSYMBOL
       WHEN lag(MSYMBOL,1) over (order by MDATE) = lag(MSYMBOL,2) over (order by MDATE)
       THEN lag(MSYMBOL,1) over (order by MDATE)
       ELSE lag(MSYMBOL,2) over (order by MDATE)
       END as FLAG
from   MYTABLE

哪些输出：

MDATE	MSYMBOL	FLAG
01-NOV-21
02-NOV-21
03-NOV-21
04-NOV-21
05-NOV-21	Square
06-NOV-21	Circle
07-NOV-21	Circle	Circle
08-NOV-21	Circle	Circle
09-NOV-21	Square	Circle

db小提琴here