“ THEN ”处或附近的 Postgresql 语法错误

Question

我正在尝试在 Postgresql 中创建一个视图，但是当我运行此代码时出现此错误：

“THEN”或附近的语法错误

CREATE OR REPLACE VIEW VW_MONITOR_DEVICE AS
    SELECT
        P.POSIZIONE_DEVICE_ID AS MONITOR_DEVICE_ID,
        P.VALID AS VALID,
         [...]
        IF (VALID == FALSE THEN 'Valid' ELSE P.REASON_FOR_INVALID) AS DESCRIPTION,
         [...]
    FROM public.TA_POSIZIONI_DEVICE P
    JOIN ...

TA_POSIZIONI_DEVICE

• 有效（布尔值不为空）

Answer 1

你应该使用CASE

SQL CASE 表达式是一个通用的条件表达式，类似 if/else 其他编程语言中的语句

CASE WHEN condition THEN result
     [WHEN ...]
     [ELSE result]
END

所以，

CREATE OR REPLACE VIEW VW_MONITOR_DEVICE AS
    SELECT
        P.POSIZIONE_DEVICE_ID AS MONITOR_DEVICE_ID,
        P.VALID AS VALID,
         [...]
           CASE WHEN VALID = false THEN 'Valid'
                ELSE P.REASON_FOR_INVALID
           END AS DESCRIPTION,

         [...]
    FROM public.TA_POSIZIONI_DEVICE P
    JOIN ...

Answer 2

你可以用例

case when VALID = FALSE THEN 'Valid' ELSE P.REASON_FOR_INVALID end DESCRIPTION,

Answer 3

IF (VALID == FALSE) THEN 'Valid' ELSE P.REASON_FOR_INVALID END IF AS DESCRIPTION

试试这个！你的情况有括号问题