Question

我需要选择一个表列值和一些常量变量。例如，

SQL表：


Key  KeyName
-------------
1    Normal
2    Basic
3    Super

常数值为R1，R2，R3，R4。

输出结果为单列：


Normal R1
Normal R2
Normal R3
Normal R4
Basic  R1
Basic  R2
.
.
.
Super  R4

欣赏任何建议。谢谢。

Answer 1

试试这个：

SELECT 
  T.KeyName,
  TT.ConstValues
FROM Tbl T
  CROSS JOIN
  (VALUES ('R1'), ('R2'), ('R3'), ('R4')) TT(ConstValues)

<强> SQL FIDDLE DEMO

Answer 2

您需要将常量值表示为结果集，然后您可以通过从两者中选择来获取笛卡尔积。例如：

WITH ConstantValues AS
(
   SELECT 'R1' AS ConstantValue
   UNION ALL 
   SELECT 'R2'
   UNION ALL 
   SELECT 'R3'
   UNION ALL 
   SELECT 'R4'
)

SELECT t.KeyName, c.ConstantValue
FROM SqlTable t, ConstantValues c;

如果您希望将每对结果表示为单个结果，则可以改为使用SELECT t.KeyName + ' ' + c.ConstantValue AS ResultColumn。

Answer 3

SELECT KeyName, Value = CASE WHEN [number] = 1 THEN 'R1' 
                             WHEN [number] = 2 THEN 'R2'
                             WHEN [number] = 3 THEN 'R3'
                             WHEN [number] = 4 THEN 'R4'
                             ELSE ''
                        END
FROM (SELECT KeyName, ROW_NUMBER OVER (PARTITION BY KeyName 
                                       ORDER BY KeyName) AS [number]
      FROM MyTable) A

选择常量变量查询

3 个答案: