Question

有没有办法在select语句中包含自定义表？

这样的事情：

select id from (1, 2, 3, 4) tbl

假设tbl是别名，而自定义表有一列包含1,2,3,4行。

这是否可以在不创建物理临时表的情况下实现？

Answer 1

是的，您可以像 Oracle 中那样（数字表）：

 with tbl as (
          -- generates table with id column with 1, 2, 3, 4 values
      select level id
        from dual
  connect by level <= 4) 

  select id 
    from tbl

您可以使用不同的语法：

select id 
  from     (select level id
              from dual
        connect by level <= 4) tbl

如果您需要任意值，请说1, 5, 14, 127您可以这样做：

with tbl as (
     select 1 from dual
  union all 
     select 5 from dual
  union all 
     select 14 from dual
  union all 
     select 127 from dual
)

select id
  from tbl

或

   select id
     from (select 1 from dual
            union all 
           select 5 from dual
            union all 
           select 14 from dual
            union all 
           select 127 from dual) tbl

如果您希望使用from (1, 2, 3)之类的语法，则必须声明类型

  create or replace type NumberTable is table of number;

  ...

  select *
    from table(NumberTable(1, 2, 3, 4)) tbl

Answer 2

create or replace type char_int is table of integer;
/



with numbers as (select column_value
                 from table(char_int(1,2,5,6,7)))
select numbers.column_value
,           object_name
,           object_id
from all_objects
join numbers on (substr(object_id,1,1) = numbers.column_value); 
;

输出：

<snip>
    1   V$HS_AGENT  1999
    2   V$HS_SESSION    2001
<snip>

是否可以在sql语句中定义表？

2 个答案: