Friday, November 25, 2011

How to Call Oracle PL SQL from Java

PL/SQL Stored Procedures


Oracle JDBC drivers support execution of PL/SQL stored procedures and anonymous blocks. They support both SQL92 escape syntax and Oracle PL/SQL block syntax. The following PL/SQL calls would work with any Oracle JDBC driver:
// SQL92 syntax
CallableStatement cs1 = conn.prepareCall
                       ( "{call proc (?,?)}" ) ; // stored proc
CallableStatement cs2 = conn.prepareCall
                       ( "{? = call func (?,?)}" ) ; // stored func
// Oracle PL/SQL block syntax
CallableStatement cs3 = conn.prepareCall
                       ( "begin proc (?,?); end;" ) ; // stored proc
CallableStatement cs4 = conn.prepareCall
                       ( "begin ? := func(?,?); end;" ) ; // stored func

As an example of using Oracle syntax, here is a PL/SQL code snippet that creates a stored function. The PL/SQL function gets a character sequence and concatenates a suffix to it:
create or replace function foo (val1 char)
return char as
begin
   return val1 || 'suffix';
end;
Your invocation call in your JDBC program should look like:
Connection conn = DriverManager.getConnection 
                  ("jdbc:oracle:oci:@", "scott", "tiger");

CallableStatement cs = conn.prepareCall ("begin ? := foo(?); end;");
cs.registerOutParameter(1,Types.CHAR);
cs.setString(2, "aa");
cs.executeUpdate();
String result = cs.getString(1);

Calling PL SQL from Java


JDBC and SQLJ allow you to call PL/SQL stored functions and procedures. For example, suppose you want to call the following stored function, which returns the balance of a specified bank account:
FUNCTION balance (acct_id NUMBER) RETURN NUMBER IS
  acct_bal NUMBER;
BEGIN
  SELECT bal INTO acct_bal FROM accts
    WHERE acct_no = acct_id;
  RETURN acct_bal;
END;
From a JDBC program, your call to the function balance might look like this:
CallableStatement cstmt = conn.prepareCall("{? = CALL balance(?)}");
cstmt.registerOutParameter(1, Types.FLOAT);
cstmt.setInt(2, acctNo);
cstmt.executeUpdate();
float acctBal = cstmt.getFloat(1);

Calling a Stored Procedure in a Database

This example demonstrates how to call stored procedures with IN, OUT, and IN/OUT parameters.
CallableStatement cs;
    try {
      // Call a procedure with no parameters
        cs = connection.prepareCall("{call myproc}");
        cs.execute();
    
      // Call a procedure with one IN parameter
        cs = connection.prepareCall("{call myprocin(?)}");
    
        // Set the value for the IN parameter
        cs.setString(1, "a string");
    
        // Execute the stored procedure
        cs.execute();
    
      // Call a procedure with one OUT parameter
        cs = connection.prepareCall("{call myprocout(?)}");
    
        // Register the type of the OUT parameter
        cs.registerOutParameter(1, Types.VARCHAR);
    
        // Execute the stored procedure and retrieve the OUT value
        cs.execute();
        String outParam = cs.getString(1);     // OUT parameter
    
      // Call a procedure with one IN/OUT parameter
        cs = connection.prepareCall("{call myprocinout(?)}");
    
        // Register the type of the IN/OUT parameter
        cs.registerOutParameter(1, Types.VARCHAR);
    
        // Set the value for the IN/OUT parameter
        cs.setString(1, "a string");
    
        // Execute the stored procedure and retrieve the IN/OUT value
        cs.execute();
        outParam = cs.getString(1);            // OUT parameter
    } catch (SQLException e) {
    }

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