Question

可以使用以下内容创建包含一列和一行的表：

select 'create' as col from dual;

这可用于构建表连接：

with
  a as (select 'create' as ac from dual),
  b as (select 'delete' as bc from dual)
select * from a left outer join b on (ac = bc);

现在我想要两行。我是这样做的：

select 'create' as col from dual
union
select 'delete' as col from dual;

但这有更紧凑的符号吗？我试过了

select ('create', 'delete') as col from dual;

但它不起作用。

Answer 1

例如，您可以使用集合类型和TABLE运算符（适用于Oracle 10g）：

SQL> SELECT column_value FROM TABLE(SYS.ODCIVARCHAR2LIST('abc', 'def', 'ghi'));

COLUMN_VALUE
--------------------------------------------------------------------------------
abc
def
ghi

Answer 2

生成行的几种方法。您可以对具有更多行的表使用rownum：

SELECT roWnum AS a
  FROM user_objects
  WHERE rownum <= 3

您可以使用分层查询：

SELECT level AS a
  FROM dual
  CONNECT BY LEVEL <= 3

编辑：将int序列更改为alpha序列：

SELECT CHR( ASCII('a') + level - 1 )
  FROM dual
  CONNECT BY LEVEL <= 3

如何在Oracle中编写表格文字？

2 个答案: