-3

我必须编写 SQL 语句来切换 in 的值，CompanyName以便table1当前具有该值的所有行都具有'Linens and Things'该值'Lamps and Lighting'，并且当前具有该值的所有行都具有该'Lamps and Lighting'值'Linens and Things'。

我的桌子目前看起来像这样：

id  CompanyName
--- ----------------------
1   'Linens and Things'
2   'Linens and Things'
3   'Lamps and Lighting'
4   'Lamps and Lighting'
5   'A Different Vendor'

更新后，它应该如下所示：

id  CompanyName
--- ----------------------
1   'Lamps and Lighting'
2   'Lamps and Lighting'
3   'Linens and Things'
4   'Linens and Things'
5   'A Different Vendor'
4

3 回答 3

3

不确定这是您想要的：

UPDATE table1
SET CompanyName = CASE WHEN CompanyName = 'Linens and Things' THEN 'Lamps and Lighting'
                       WHEN CompanyName = 'Lamps and Lighting' THEN 'Linens and Things'
                       ELSE CompanyName
                       END
WHERE CompanyName IN ('Linens and Things','Lamps and Lighting')
于 2013-11-05T06:01:04.613 回答
0

当您反转这些值时，您需要进行 3 个不同的更新（3 个步骤），如下所示；

Step1：更改现有“Linens and Things”的值；

Update table1 set CompanyName = "x"
where  CompanyName = "Linens and Things"

Step2：将供应商“Lamps and Lighting”修改为“Linens and Things”；

Update table1 set CompanyName = "Linens and Things"
where  CompanyName = "Lamps and Lighting"

Step3：将最初“Linens and Things”的供应商修改为“Lamps and Lighting”；

Update table1 set CompanyName = "Lamps and Lighting"
where  CompanyName = "x"
于 2013-11-05T05:36:07.487 回答
0

T-SQL 的 UPDATE 语句有一个 FROM 子句，允许您在更新表之前计算它。对于这种情况，我们可以将新名称计算为AlternateCompanyName和 set CompanyName=AlternateCompanyName。

UPDATE table1
SET CompanyName = ComputedTable.AlternateCompanyName
FROM (
    SELECT
        id,
        CompanyName,
        CASE
          WHEN CompanyName = 'Linens and Things' THEN 'Lamps and Lighting'
          WHEN CompanyName = 'Lamps and Lighting' THEN 'Linens and Things'
        END AS AlternateCompanyName
    FROM table1
) AS ComputedTable
JOIN table1 ON table1.id = ComputedTable.id
WHERE table1.CompanyName IN ('Lamps and Lighting', 'Linens and Things')
于 2013-11-05T06:34:27.753 回答