多次自连接替换

Question

Want some replacement for multiple self join on a table. what is the maximum limit of self join on a table in SQL

I have a table table_1 with columns as:

uid number(10),
a_name nvarchar(20),
aaId number (10),

where unique constraint is there on combination of uid and aaId.

data present in table is like. for each aaId there are around 90 Uid's.

now my query is like

select aaId from table_1 
  inner join table_1 t1 on t1.uid=9 and t1.a_name like 'a'  
  inner join table_1 t2 on t2.uid=8 and t2.a_name like 'ab'  
  inner join table_1 t3 on t3.uid=7 and t3.a_name like 'ac'

My problem is number of inner join has increased to 90 . as rows in table is around 2 lakh will this query work . Or if there is anything else I can do to replace this large number of self joins.

Please help.

Thanks in advance.

Answer 1

First of all, why don't you use the WHERE part with OR statement?

select aaId from table_1 
WHERE (table_1.uid=9 and table_1.a_name like 'a') OR 
(table_1.uid=8 and table_1.a_name like 'ab') OR
(table_1.uid=7 and table_1.a_name like 'ac')

Answer 2

Please try this query which is used self join and required conditions

select aaId from table_1 t1, table_1 t2 where (t1.uid=9 and t2.a_name like 'a') or (t1.uid=8 and t2.a_name like 'ab')