SQL DB2将查询结果存储到变量中

Question

Usind a DB2 tables: This is what is done manually in a table

select app_id from table_app where APP_NAME='App_Temp';

gets me an ID, say it's 234

I copy than and do:

select * form table_roles where role_app_id=234;

gets me a row , which is my desired end result.

Is there a way save the result of the first one into a variable and do the second query without the manual step in between using local variables?

I know, you can query out the information with a very simple join between two tables, but I'd like to know, how it works with variables. Is there a way?

Answer 1

Just can just plug it in:

select *
from table_roles
where role_app_id = (select app_id from table_app where APP_NAME = 'App_Temp');

If there can be more than one match, use in instead of = .

You can also phrase this as a join:

select r.*
from table_roles r join
     table_app
     on r.role_app_id = a.app_id and APP_NAME = 'App_Temp';

However, this might return duplicates, if two apps have the same name. In that case, use select distinct :

select distinct r.*
from table_roles r join
     table_app
     on r.role_app_id = a.app_id and APP_NAME = 'App_Temp';