使用 if 查询并声明

Question

如何进行这样的查询？

SELECT 
PersonId, 
Name,
(
    DECLARE @p INT=(SELECT (Not1 + Not2 + Not3)/3 FROM Tablo_Not WHERE NotId=PersonId);
    DECLARE @s INT;
    IF @p>84
        SET @s=5;
    ELSE IF @p>69
        SET @s=4;
    ELSE IF @p>54
        SET @s=3;
    ELSE IF @p>44
        SET @s=2;
    ELSE
        SET @s=1;
    SELECT @s;
) AS Degree
FROM Tablo_Person;

Answer 1

您不能在这样的

DECLARE

查询中使用

SELECT

语句。但是，您可以通过使用

CASE

表达式而不是

DECLARE

和

IF

语句来实现结果。

SELECT 
    PersonId, 
    Name,
    CASE 
        WHEN (SELECT (Not1 + Not2 + Not3)/3 FROM Tablo_Not WHERE NotId = PersonId) > 84 THEN 5
        WHEN (SELECT (Not1 + Not2 + Not3)/3 FROM Tablo_Not WHERE NotId = PersonId) > 69 THEN 4
        WHEN (SELECT (Not1 + Not2 + Not3)/3 FROM Tablo_Not WHERE NotId = PersonId) > 54 THEN 3
        WHEN (SELECT (Not1 + Not2 + Not3)/3 FROM Tablo_Not WHERE NotId = PersonId) > 44 THEN 2
        ELSE 1
    END AS Degree
FROM Tablo_Person;