如何在 REPLACE () 语句中使用和 IF 语句？

Question

收到关于在 REPLACE 语句中使用 IF 语句的查询（如果可能的话！）

例子：

REPLACE("Person Legislative Information"."Marital Status",'Widowed','Widower')

这样行得通，但我需要一个 IF 语句来根据他们的性别区分他们是鳏夫还是寡妇（可以从另一列中提取）。

我会在开始 REPLACE 语句之前放置一个 IF 语句吗？

例子：

REPLACE(REPLACE(IF("Worker"."Gender" = 'M')"Person Legislative Information"."Marital Status",'Widowed','Widower')IF("Worker"."Gender" = 'F')"Person Legislative Information"."Marital Status",'Widowed','Widow')

不确定我是否嵌套了这个错误，但我似乎无法让它工作，有什么想法吗？

Answer 1

我认为您正在寻找 CASE 声明

SELECT
  CASE "Worker"."Gender"
    WHEN 'F' THEN
      REPLACE("Person Legislative Information"."Marital Status", 'Widowed', 'Widow')
    ELSE
      REPLACE("Person Legislative Information"."Marital Status", 'Widowed', 'Widower')
  END marital_status

Answer 2

您可以使用case expression 来决定使用哪个替换值：

REPLACE("Person Legislative Information"."Marital Status",
    'Widowed', CASE "Worker"."Gender" WHEN 'F' THEN 'Widow' ELSE 'Widower' END)

演示：

with "Worker" (id, "Gender") as (
  select 1, 'M' from dual
  union all select 2, 'F' from dual
),
"Person Legislative Information" (id, "Marital Status") as (
  select 1, 'Widowed' from dual
  union all select 2, 'Widowed' from dual
)
SELECT "Worker"."Gender", "Person Legislative Information"."Marital Status",
  REPLACE("Person Legislative Information"."Marital Status",
    'Widowed', CASE "Worker"."Gender" WHEN 'F' THEN 'Widow' ELSE 'Widower' END)
    AS "New Marital Status"
FROM "Worker"
JOIN "Person Legislative Information"
ON "Person Legislative Information".id = "Worker".id;

G Marital New Marital Status                               
- ------- -------------------------------------------------
M Widowed Widower                                          
F Widowed Widow