基于现有表创建一个新表

Question

我想在Access 2003中编写一个查询，该查询基于现有表创建一个新表。 我正在使用Make Table Query。

前：

NAME A_1 A_2 B_1 B_2 
X  1 2 3  4 
Y  5 6 7  8 

后

NAME Section Value1 Value2 
X   A 1  2 
X   B 3  4 
Y   A 5  6 
Y   B 7  8 

Answer 1

创建SELECT查询，从现有的表的每一行中检索A_1和A_2值：

SELECT e1.NAME, 'A' AS [Section], e1.A_1 AS Value1, e1.A_2 AS Value2 
FROM tblExisting AS e1 

然后创建以检索B_1和B_2值，并UNION两个SELECT语句类似的查询：

SELECT e1.NAME, 'A' AS [Section], e1.A_1 AS Value1, e1.A_2 AS Value2 
FROM tblExisting AS e1 
UNION ALL 
SELECT e2.NAME, 'B' AS [Section], e2.B_1 AS Value1, e2.B_2 AS Value2 
FROM tblExisting AS e2 

从那里，你可以建立基于该UNION查询生成表查询：

SELECT sub.* 
    INTO tblNew 
FROM 
    (
     SELECT e1.NAME, 'A' AS [Section], e1.A_1 AS Value1, e1.A_2 AS Value2 
     FROM tblExisting AS e1 
     UNION ALL 
     SELECT e2.NAME, 'B' AS [Section], e2.B_1 AS Value1, e2.B_2 AS Value2 
     FROM tblExisting AS e2 
    ) AS sub;