ORACLE SQL CASE 语句 - 出现错误答案

【问题标题】：ORACLE SQL CASE statement - getting errorORACLE SQL CASE 语句 - 出现错误
【发布时间】：2020-11-19 07:07:32
【问题描述】：

SELECT
    ZOC, UNIT,
    CASE ZOC
        WHEN ZOC = '51' THEN 'ZONE OPERATION KHULNA'
        WHEN ZOC = '52' THEN 'ZONE OPERATION JESSORE'
        WHEN XOC = '53' THEN 'ZONE OPERATION KUSHTIA'
    END
FROM 
    GNGRB.BS_CLOSING
ORDER BY 
    ZOC;

我收到此错误：

ORA-00905：缺少关键字
00905. 00000 - “缺少关键字”
*原因：
*行动：
行错误：16 列：10

【问题讨论】：

附带说明：zoc 是字符串列还是为什么要使用引号（'51' 等）？如果是数字列，则应使用数字，例如WHEN ZOC = 51.
最好的解决方案当然是将区域字符串映射到区域编号的区域表，但我想你知道。

标签： sql oracle syntax-error

【解决方案1】：

您正在混合两种语法。决定一个。

`CASE zoc WHEN ...`

SELECT 
  zoc, unit,
  CASE zoc
    WHEN 51 THEN 'ZONE OPERATION KHULNA'
    WHEN 52 THEN 'ZONE OPERATION JESSORE'
    WHEN 53 THEN 'ZONE OPERATION KUSHTIA'
  END 
FROM ...

`CASE WHEN ...`

SELECT 
  zoc, unit,
  CASE
    WHEN zoc = 51 THEN 'ZONE OPERATION KHULNA'
    WHEN zoc = 52 THEN 'ZONE OPERATION JESSORE'
    WHEN zoc = 53 THEN 'ZONE OPERATION KUSHTIA'
  END 
FROM ...

【讨论】：

【解决方案2】：

SELECT ZOC, UNIT, CASE WHEN ZOC = '51' THEN 'ZONE OPERATION KHULNA'
                       WHEN ZOC = '52' THEN 'ZONE OPERATION JESSORE'
                       WHEN ZOC = '53' THEN 'ZONE OPERATION KUSHTIA'
                  END 
FROM GNGRB.BS_CLOSING 
ORDER BY ZOC;

【讨论】：

【解决方案3】：

CASE..WHEN 语句有两种写法。

CASE WHEN COLUMN_NAME = VALUE1 THEN ... WHEN COLUMN_NAME = VALUE2 THEN .. END
CASE COLUMN_NAME WHEN VALUE1 THEN ... WHEN VALUE2 THEN ... END

在你的情况下，你可以这样写：

SELECT ZOC,
       UNIT,
       CASE 
       --ZOC -- just remove this
           WHEN ZOC = '51' THEN
               'ZONE OPERATION KHULNA'
           WHEN ZOC = '52' THEN
               'ZONE OPERATION JESSORE'
           WHEN ZOC = '53' THEN
               'ZONE OPERATION KUSHTIA'
       END
  FROM GNGRB.BS_CLOSING
 ORDER BY ZOC;

-- 或

SELECT ZOC,
       UNIT,
       CASE ZOC
           WHEN '51'   THEN
               'ZONE OPERATION KHULNA'
           WHEN '52'   THEN
               'ZONE OPERATION JESSORE'
           WHEN '53'   THEN
               'ZONE OPERATION KUSHTIA'
       END
  FROM GNGRB.BS_CLOSING
 ORDER BY ZOC;

【讨论】：