SQL自定义选择

Question

我想写一个给出以下结果的sql。这可能吗？ 我试过UNION但它只适用于一个记录。

 
col1 | col2 | col3 | col4 
--------------------------- 
    A | 10 |  | 
     | 2 | val1 | val2 
     | 5 | val3 | val4 
     | 3 | val5 | val6 
    B | 11 |  | 
     | 3 | val7 | val8 
     | 5 | val9 | val10 
     | 3 | val0 | val12 

这里我的查询：

SELECT a.val1, NULL val2, a.val3 FROM table1 a 
WHERE a.val1 = 'A' 
UNION 
SELECT NULL val1, b.val2, b.val3 FROM table2 b 
WHERE b.val1 = 'A' ; 

也许这会让问题更加清晰。

试想一下，如果我运行查询：

SELECT a.val1, NULL val2, a.val3 FROM table1 a 
UNION 
SELECT NULL val1, b.val2, b.val3 FROM table2 b ; 

我想要的结果设置为如上图所示。

 
col1 | col2 | col3 | col4 
--------------------------- 
    A | 10 |  | 
     | 2 | val1 | val2 
     | 5 | val3 | val4 
     | 3 | val5 | val6 
    B | 11 |  | 
     | 3 | val7 | val8 
     | 5 | val9 | val10 
     | 3 | val0 | val12 

Answer 1

无论汇总或常规组能做到这一点，但你还没有占到col2。从哪里来的，就像你的sql片段一样，你根本就没有它。

SQL> create table yourtab(col1, col2, col3, col4) 
    2 as 
    3 select 'A', 2, 'val1', 'val2' from dual 
    4 union all select 'A', 5, 'val3', 'val4' from dual 
    5 union all select 'A', 3, 'val5', 'val6' from dual 
    6 union all select 'B', 3, 'val7', 'val8' from dual 
    7 union all select 'B', 5, 'val9', 'val10' from dual 
    8 union all select 'B', 3, 'val11', 'val12' from dual; 

Table created. 

SQL> 
SQL> select col1, sum(col2) col2, col3, col4 
    2 from yourtab 
    3 group by col1, rollup(col3, col4) 
    4 having (grouping_id(col3), grouping_id(col4)) in ((0,0),(1,1)) 
    5 order by col1, grouping_id(col3) desc; 

C  COL2 COL3 COL4 
- ---------- ----- ----- 
A   10 
A   5 val3 val4 
A   3 val5 val6 
A   2 val1 val2 
B   11 
B   3 val7 val8 
B   5 val9 val10 
B   3 val11 val12 

8 rows selected. 

SQL> 
SQL> select col1, col2, col3, col4 
    2 from (select col1, col2, col3, col4, 2 grp 
    3   from yourtab 
    4   union all 
    5   select col1, sum(col2), null, null, 1 grp 
    6   from yourtab 
    7   group by col1) 
    8 order by col1, grp; 

C  COL2 COL3 COL4 
- ---------- ----- ----- 
A   10 
A   5 val3 val4 
A   3 val5 val6 
A   2 val1 val2 
B   11 
B   3 val11 val12 
B   5 val9 val10 
B   3 val7 val8 

8 rows selected.