I have created a function myresult() that receives as input Table name, and a Prefix, it then creates an SQL one liner command to SELECT from the specified table only the columns that share the designated prefix. It output a string which is basically the desired SQL command. My function is as follows and I show how I call it as well:
CREATEOR REPLACE FUNCTION myresult(mytable text, myprefix text)
RETURNS text AS$func$DECLARE myoneliner text;BEGINSELECTINTO myoneliner 'SELECT '|| string_agg(quote_ident(column_name::text),','ORDERBY column_name)||' FROM '|| quote_ident(mytable)FROM information_schema.columns WHERE table_name = mytable AND column_name LIKE myprefix||'%'AND table_schema ='public';-- schema name; might be another param
RAISE NOTICE 'My additional text: %', myoneliner;RETURN myoneliner;END$func$ LANGUAGE plpgsql;--now call functionselect myresult('dkj_p_k27ac','enri');
--now call the function:
select myresult('dkj_p_k27ac','enri');
And now, upon running the above procedure - I get a text string, which is basically a query (I'll refer to it up next as 'oneliner-output', just for simplicity). The 'oneline-output' looks as follows (i just copy/paste it from the one output cell that i've got into here):
"SELECT enrich_d_dkj_p_k27ac,enrich_lr_dkj_p_k27ac,enrich_r_dkj_p_k27ac FROM dkj_p_k27ac"
please note that the double quotes from both sides of the statement were part of the myresult() output (i didn't add them by myself).
basically, I am able to copy/paste the 'oneliner-output' into a new postgres query window and execute it as a normal query just fine - receiving the desired columns and rows in my Data Output window. I would like however to automate this step, so to avoid the copy/paste step. Is there a way in postgres to use the TEXT output (the 'oneliner-output') that I receive from myresult() function, and execute it? Can a second function be created that would receive the output of myresult() and use it for executing a query?
Along these lines, while I know that this scripting works and actually output exactly the desired columns and rows:
--DEALLOCATE stmt1; -- use this line after the first time 'stmt1' was created
prepare stmt1 asSELECT enrich_d_dkj_p_k27ac,enrich_lr_dkj_p_k27ac,enrich_r_dkj_p_k27ac FROM dkj_p_k27ac;execute stmt1;
I was thinking maybe something like the following scripting could work, after doing the right tweaking?? Not sure how though..
prepare stmt1 as THE_OUTPUT_OF_myresult();execute stmt1;
