Question

希望创建一个Update查询，根据同一个表中另一列的值设置列中的值，例如：

UPDATE mytable
SET field1 = CASE field2
         WHEN field2 = 1 THEN "ASG1"
         WHEN field2 = 2 THEN "ASG2"
         WHEN field2 = 3 THEN "ASG3"
         WHEN field2 = 4 THEN "ASG4"
         WHEN field2 = 5 THEN "ASG5"
         ELSE Field1 (retaining old value)
         END
WHERE field2 IN (1,2,3,4,5)

无论我尝试什么，我一直搞砸了声明

当前和更新形式的数据示例如下：

field1 field2
value    1
value    2
value    3

field1 field2
asg1     1
asg2     2
asg3     3

Answer 1

Access SQL不支持CASE ... WHEN。您可以使用Switch表达式代替......

UPDATE mytable
SET field1 = 
    Switch
        (
            field2 = 1, "ASG1",
            field2 = 2, "ASG2",
            field2 = 3, "ASG3",
            field2 = 4, "ASG4",
            field2 = 5, "ASG5"
        )
WHERE field2 IN (1,2,3,4,5)

但是，您可以通过这个更简单的UPDATE ...

获得所需的结果

UPDATE mytable AS m
SET m.field1 = 'ASG' & [m].[field2]
WHERE m.field2 In (1,2,3,4,5);

SQL使用UPDATE / CASE / WHEN

1 个答案: