How to fet a variable from a query?

In a function I am making a query.

I want to fetch a variable say c which I will get when this query will run once. if the c variable is not 0 the same query should run again till the c value is 0. o/p

sql>> select * from  table_sql;
a | b | c |d | e | f |g | h
1   3   2   1  5   h   3   2

so if the c value is not zero after the 1st query is executed the same query should run again.

How in the 1st query I can get the value of c variable?