oracle - Call pl/sql function in java?

Question

So I've got a function that checks how many cancellations are in my booking table:

CREATE OR REPLACE FUNCTION total_cancellations
RETURN number IS
   t_canc number := 0;
BEGIN
   SELECT count(*) into t_canc
   FROM booking where status = 'CANCELLED';
   RETURN t_canc;
END;
/

To execute his in sql I use:

set serveroutput on
DECLARE
   c number;
BEGIN
   c := total_cancellations();
   dbms_output.put_line('Total no. of Cancellations: ' || c);
END;
/

My result is:

anonymous block completed
Total no. of Cancellations: 1

My question is can someone help me call the function in JAVA, I have tried but with no luck.

Answer 1

Java provides CallableStatements for such purposes .

CallableStatement cstmt = conn.prepareCall("{? = CALL total_cancellations()}");
cstmt.registerOutParameter(1, Types.INTEGER);
cstmt.setInt(2, acctNo);
cstmt.executeUpdate();
int cancel= cstmt.getInt(1);
System.out.print("Cancellation is "+cancel);

will print the same as you do in the pl/sql. As per docs Connection#prepareCall(),

Creates a CallableStatement object for calling database stored procedures. The CallableStatement object provides methods for setting up its IN and OUT parameters, and methods for executing the call to a stored procedure.

You can also pass parameters for the function . for ex ,

conn.prepareCall("{? = CALL total_cancellations(?)}");
cstmt.setInt(2, value);

will pass the values to the function as input parameter.

Hope this helps !