Task 2 plpgsql done

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diff --git a/challenge-194/luca-ferrari/postgresql/ch-2.sql b/challenge-194/luca-ferrari/postgresql/ch-2.sql
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+-- Perl Weekly Challenge 194
+-- Task 2
+
+CREATE SCHEMA IF NOT EXISTS pwc194;
+
+CREATE OR REPLACE FUNCTION
+pwc194.task2_plpgsql( what text)
+RETURNS int
+AS $CODE$
+DECLARE
+	t text;
+	current_max int;
+	current_min int;
+	current_count int;
+BEGIN
+	CREATE TEMPORARY TABLE IF NOT EXISTS counter ( l char, c int, PRIMARY KEY(l) );
+	TRUNCATE counter;
+
+	FOR t IN SELECT v FROM regexp_split_to_table( what, '' ) v LOOP
+	    INSERT INTO counter AS cnt ( l, c )
+	    VALUES ( t, 1 )
+	    ON CONFLICT (l)
+	    DO UPDATE SET c = cnt.c + 1;
+	END LOOP;
+
+	SELECT max(c), min(c)
+	INTO current_max, current_min
+	FROM counter;
+
+	IF current_max - current_min <> 1 THEN
+	   RETURN 0;
+	END IF;
+
+	SELECT count(*)
+	INTO current_count
+	FROM counter
+	WHERE c = current_max;
+
+	IF current_count <> 1 THEN
+	   RETURN 0;
+	END IF;
+
+	RETURN 1;
+END
+$CODE$
+LANGUAGE plpgsql;