Make in (SQL) dynamic for incoming values - sql

Question

Is it possible for in statement to be dynamic? like dynamic comma separation
for example:
DATA=1
select * from dual
where
account_id in (*DATA);
DATA=2
select * from dual
where
account_id in (*DATA1,*DATA2);
FOR DATA=n
how will i make the in statement dynamic/flexible (comma) for unknown quantity.
select * from dual
where
account_id in (*DATAn,*DATAn+1,etc);

Answer 1

A hierarchical query might help.
acc CTE represents sample data
lines #9 - 11 are what you might be looking for; data is concatenated with level pseudocolumn's value returned by a hierarchical query
Here you go:
SQL> with acc (account_id) as
2 (select 'data1' from dual union all
3 select 'data2' from dual union all
4 select 'data3' from dual union all
5 select 'data4' from dual
6 )
7 select *
8 from acc
9 where account_id in (select 'data' || level
10 from dual
11 connect by level <= &n
12 );
Enter value for n: 1
ACCOU
-----
data1
SQL> /
Enter value for n: 3
ACCOU
-----
data1
data2
data3
SQL>

Answer 2

As I can see, You are using the number in Where clause, Substitution will be enough to solve your problem.
See the example below:
CREATE table t(col1 number);
insert into t values(1);
insert into t values(2);
insert into t values(3);
-- Substitution variable initialization
define data1=1;
define data2='1,2';
--
-- With data1
select * from t where col1 in (&data1);
Output:
-- With data2
select * from t where col1 in (&data2);
Output:
Hope, This will be helpful to you.
Cheers!!

Answer 3

The basic problem is not the listagg function but a major misconception that just because elements in a string list are comma separated that a string with commas in it is a list. Not So. Consider a table with the following rows.
Key
- Data1
- Data2
- Data1,Data2
And the query: Select * from table_name where key = 'wanted_key'; Now if all commas separate independent elements then what value in for "wanted_Key" is needed to return only the 3rd row above? Even with the IN predicate 'Data1,Data2' is still just 1 value, not 2. For 2 values it would have to be ('Data1','Data2').
The problem you're having with Listagg is not because of the comma but because it's not the appropriate function. Listagg takes values from multiple rows and combines then into a single comma separated string but not comma separated list. Example:
with elements as
( select 'A' code, 'Data1' item from dual union all
select 'A', 'Data2' from dual union all
select 'A', 'Data3' from dual
)
select listagg( item, ',') within group (order by item)
from elements group by code;
(You might also want to try 'Data1,Data2' as a single element. Watch out.
What you require is a query that breaks out each element separately. This can be done with
with element_list as
(select 'Data1,Data2,Data3' items from dual) -- get paraemter string
, parsed as
(select regexp_substr(items,'[^,]+',1,level) item
from element_list connect by regexp_substr(items,'[^,]+',1,level) is not null -- parse string to elements
)
The CTE "parsed" can now be used as table/view in your query.
This will not perform as well as querying directly with a parameter, but performance degradation is the cost of dynamic/flexible queries.
Also as set up this will NOT handle parameters which contain commas within an individual element. That would require much more code as you would have to determine/design how to keep the comma in those elements.