Invalid Column Index with PL/SQL Functions

Question

I am trying to make a simple PL/SQL-to-Java setup, where I make a function in PL/SQL and call it from Java, expecting a return value.

I am fairly new to PL/SQL and calling it in Java so my approach is probably just lacking understanding in how return values from SQL actually works.

My SQL Function looks like this:

CREATE OR REPLACE FUNCTION GET_BOOKED_COUNT(P_NO VARCHAR2)
  RETURN NUMBER AS
  RESULTS NUMBER := 0;
BEGIN
  SELECT COUNT(*) INTO RESULTS FROM SEAT WHERE PLANE_NO=P_NO AND BOOKED IS NULL;
  RETURN RESULTS;
END GET_BOOKED_COUNT;

Return a number pretty much. It needs to check a table of seats to see how many of them are not booked yet.

After trying to follow various other Stackoverflow posts, I tried to duplicate what they did but it keeps telling me that the Index Column is Invalid.

public static boolean isAllBooked(String plane_no) {
    String sql = "{? = CALL GET_BOOKED_COUNT('?')}";
    boolean res = false;
    try {
        Connection conn = getConnection("db_010", "db2014");
        CallableStatement cs = conn.prepareCall(sql);
        cs.setString(2, plane_no);
        cs.registerOutParameter(1, Types.NUMERIC);
        cs.executeUpdate();
        int i = cs.getInt(1);
        if(i == 0) {
            res = true;
        }
        conn.close();
    } catch (SQLException ex) {
        Logger.getLogger(HelperClass.class.getName()).log(Level.SEVERE, null, ex);
    }
    return res;
}

It's probably an easy fix, so what am I doing wrong exactly?

Answer 1

Your second bind variable, the argument to the function, should not be enclosed in single quotes. You're passing the literal value '?', not defining a bind:

String sql = "{? = CALL GET_BOOKED_COUNT(?)}";

The way you then refer to both parameters seems to be OK.