Java Programming with Oracle JDBC

The execute( ) Method

The execute( ) method is the most generic method you can use to execute a SQL statement in JDBC. To execute a SQL statement with the execute method, call it by passing it a valid SQL statement as a String object, or as a string literal, as shown in the following example:

boolean isResultSet = false;
Statement stmt = null;
try {
  stmt = conn.createStatement(  );
  isResultSet = stmt.execute("select 'Hello '||USER from dual"); 
  . . . 
}

In this example, we assume that Connection object conn already exists. First, a boolean variable named isResultSet is created to hold the return value from the call to the execute( ) method. Next, a variable named stmt is created to hold a reference to the Statement object. In the try block, the Statement object is created with a call to the Connection object’s createStatement( ) method. Then, the Statement object’s execute( ) method is called passing a SQL SELECT statement. Since this is a SELECT statement, the execute( ) method returns a boolean true to indicate that a result set is available. You can then call the Statement object’s getResultSet( ) method to retrieve the ResultSet object that contains the data from the database. For example:

boolean isResultSet = false;
Statement stmt = null;
ResultSet rslt = null;
try {
  stmt = conn.createStatement(  );
  isResultSet = stmt.execute("select 'Hello '||USER from dual"); 
  if (isResultSet) {
    rslt = stmt.getResultSet(  );
  }
  . . . 
}

We’ll cover result sets in great detail in Chapter 10.

If an INSERT, ...