【PostgreSQL】文字列から検索文字の位置を取得する(IndexOf)

CREATE OR REPLACE FUNCTION public.indexof(
	c_target_char character varying,
	c_search_char character varying)
    RETURNS integer
    LANGUAGE 'plpgsql'

    COST 100
    VOLATILE 
    
AS $BODY$
declare
BEGIN

	--文字列と検索文字列が空かnullなら0とする
	if (c_target_char is null) or (c_target_char= '') then
		return 0;
	end if;
	if (c_search_char is null) or (c_search_char = '') then
		return 0;
	end if;

	RETURN strpos(c_target_char, c_search_char);

END;
$BODY$;

ALTER FUNCTION public.indexof(character varying, character varying)
    OWNER TO postgres;

select indexOf('abcdefgh', 'f'); --【結果】:6