用Java调用PostgreSQL存储过程返回null

Question

I have the following stored procedure written in PostgreSQL 9.3 that's working perfectly:

CREATE OR REPLACE FUNCTION getColor(i INT) 
 RETURNS VARCHAR AS $varColor$
    DECLARE varColor varchar;   
    BEGIN
      select color into varColor FROM colors where id = i;
      return varColor;
    END;
    $varColor$ LANGUAGE plpgsql;

In fact, when I execute select getColor(2) in pgAdmin I get the expected value. I am trying to call it like this from Java (simplified version):

String call =  "{ call getColor(?,?) }";
CallableStatement cstmt = connection.prepareCall(call);
cstmt.setInt(1, 2);
cstmt.registerOutParameter(2, java.sql.Types.VARCHAR);
boolean hadResults = cstmt.execute();

The problem is that hadResults is always null. Any ideas?

Answer 1

Postgresql stored procedures concept is something different than other vendors like Oracle. Basically what in Oracle is called store procedure in Postgresql can be a function, and to call a function in Java is better to use prepare statements and executeQuery methods like in the following example

String call =  "select getColor(?)";
PreparedStatement pstmt = connection.prepareStatement(call);
pstmt.setInt(1,1);
Resultset resultset = pstmt.executeQuery();

Thank you to all the guys who helped in the question comments!