Error while replacing IF statements with DECODE function in procedure

Question

Hi All,
I have created a procedure which has nested IF statements. Now I want to replace the IF statements with DECODE functions to improve performance.
Procedure:
IF (var_int_sev = '0')
THEN
var_sev := '2';
ELSE
SELECT sev
INTO var_int_sev
FROM errorconfig
WHERE errorcode = var_errorcode;
var_sev := var_int_sev;
END IF;
I converted the above IF statement into DECODE function as mentioned below:
var_Sev := DECODE(var_int_sev,0,2,SELECT severity FROM errorconfig WHERE errorcode=var_ErrorCode)
But it throws below error at the select statement used inside DECODE.
Error(58,51): PLS-00103: Encountered the symbol "SELECT" when expecting one of the following: ( - + case mod new not null others <an identifier> <a double-quoted delimited-identifier> <a bind variable> avg count current exists max min prior sql stddev sum variance execute forall merge time timestamp interval date <a string literal with character set specification> <a number> <a single-quoted SQL string> pipe <an alternatively-quoted string literal with character set specification> <an alternativ
Can someone help me in converting the IF to DECODE in the above case. Also how can we use a select statement inside decode.

Answer 1

instead of trying to rewrite all your code and hoping that the performance will be better, it's a better option to investigate and find out which part of your application is slow
read this:
When your query takes too long ...