Re: PostgreSQL equivalent of Oracle "member of" - Mailing list pgsql-general

Hi Mr Kellerer

Thanks a lot for your reply and suggestion.

I will check it out.

Regards
Vadi
Bengaluru
India

On Fri, 29 Mar 2019 15:34:12 +0530 Thomas Kellerer wrote
>Vadi schrieb am 29.03.2019 um 10:44:

> I would like to know if there is any equivalent in PostgreSQL for the Oracle "member of" syntax.

>

> The usage is as shown below:

>

> I have used the Oracle sample HR schema for the below example:

>

> CREATE OR REPLACE TYPE params as table of varchar2 (100);

> /

>

> CREATE OR REPLACE function in_list (in_list in varchar2) return params pipelined as

> param_list varchar2(4000) := in_list || ',';

> pos number;

> begin

> loop

> pos := instr(param_list, ',');

> exit when nvl(pos, 0) = 0;

> pipe row (trim(substr(param_list, 1, pos - 1)));

> param_list := substr(param_list, pos + 1);

> end loop;

>

> return;

> end in_list;

> /

>

> CREATE TABLE tname as

> SELECT listagg(first_name, ', ') within group (order by first_name) first_name FROM employees;

>

> SELECT * FROM tname;

>

> SELECT * FROM employees

> WHERE first_name member of in_list(first_name);



I don't understand where the parameter to the in_list() functions comes from in the last query.

As written it would be the value from employees.first_name, which is not a comma separated list, so it doesn't really make sense.



I think what the in_list() function does, would be the equivalent to unnest/string_to_array



e.g.:



select *

from unnest(string_to_array('foo,bar', ',')) as t(name);



returns



name

----

foo

bar



If you just want to check if one string is contained in a comma separated list, you can use the ANY operator:



where first_name = any (string_to_array('foo,bar', ','))



Thomas