根据参数生成联合SQL

Question

我想编写将采用参数并基于参数创建带有参数表联合的视图的sql

目前我在下面做，但客户表的范围从R1到R40

create or replace view customers_a as 
select * from customer_R1 
UNION 
select *  from customer_R40;

现在我需要编写将参数作为

@gen.sql R1 R3 R4

并创建为

create or replace view customers_ALL as 
select * from customer_R1 
UNION 
select *  from customer_R3
UNION 
select *  from customer_R4;

根据传递的参数，它应该是动态的

Answer 1

你有考虑过吗？

create or replace view customers_ALL as 
    select 'R1' as which, c.* from customer_R1 c
    UNION ALL
    select 'R2' as which, c.* from customer_R1 c
    UNION ALL
    select 'R3', c.* from customer_R3 c
    UNION ALL
    . . .
    select 'R31', *  from customer_R31 c;

然后，您可以使用以下命令查询此视图：

select *
from customers_ALL
where which in ('R1', 'R3', 'R4')

假定表之间没有重复项。 否则，引入which将使行变得唯一（这就是为什么我将union更改为union all ）。