Question

是否可以使用自己的元组作为JOIN语句的源？

这是我正在寻找的一个例子：

SELECT u.id, u.name FROM users u INNER JOIN {{tupl1},{tupel2},{tupel3},...}

Answer 1

在SQL Server 2008中，您使用Table Value Constructor。

declare @T table(ID int)
insert into @T values (1),(2),(3),(4),(5)

select *
from @T as T1 
  inner join (
              values (1, 'Row 1'), 
                     (2, 'Row 2')
             ) as T2(ID, Col1)
    on T1.ID = T2.ID

Answer 2

许多dbms平台都支持公用表表达式。

with my_own_tuples as (
    select 'value1' as column1, 'value2' as column2
    union all 
    select 'value3', 'value4'
    union all 
    select 'value5', 'value6'
)
select column1, column2
from my_other_table
inner join my_own_tuples on (my_own_tuples.column1 = my_other_table.column1);

PostgreSQL Common Table Expressions

Answer 3

MySql有一些support for Tuples with comparisons and equality，虽然我很难找到明确的参考资料。

例如：

SELECT *
    FROM table1 t1
       INNER JOIN table2 t2
       ON (t1.Col1, t1.Col2) = (t2.Col1, t2.Col2);

和

SELECT *
    FROM table1 t1
       WHERE (t1.Col1, t1.Col2) <= ('SomeValue', 1234);

SqlFiddle showing these here

在JOIN语句中使用自己的元组

3 个答案: