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Execute Methods

1. executeQuery() This method is used to execute a SELECT statement and returns a ResultSet object that contains the data produced by the statement.

       [ResultSet](./src/result-set-methods.md) rs = stmt.executeQuery("SELECT * FROM mytable");
   

2. executeUpdate() This method is used to execute INSERT, UPDATE, or DELETE statement and returns an int value indicating the number of rows affected by the statement.

       int rowAffected = stmt.executeUpdate("UPDATE mytable SET name='manoj' WHERE id=1");
   

3. execute() This method is used to execute a SQL statement and returns a boolean value indicating whether the satement produced a ResultSet object or not.

       boolean hasResultSet = stmt.execute("SELECT * FROM mytable");
       if(hasResultSet){
           // process the result set
       }else{
           int rowAffected = stmt.getUpdateCount();
           // process the row affected
       }
   

4. executeBatch() This method is used to execute batch of SQL statements a single unit and returns an array of int values indicating the number of rows affected by each statement.

       stmt.addBatch("INSERT INTO mytable (id, name, age) VALUES (1, 'Manoj', 22)");
       stmt.addBatch("INSERT INTO mytable (id, name, age) VALUES (2, 'Rutik', 22)");
       int[] rowsAffected = stmt.executeBatch();
   

5. executeQuery(String sql, String[] columnNames) This method is used to execute an INSERT statement and returns a ResultSet object that contains the generated keys specified by the columnNames parameter.

       PreparedStatement pstmt = conn.prepareStatement("INSERT INTO mytable (name, age) VALUES (?, ?)", new String[] {"id"});
       pstmt.setString(1, "Manoj");
       pstmt.setInt(2, 22);
       pstmt.executeQuery();
       ResultSet rs = pstmt.getGeneratedKeys();
       if(rs.next()){
           int id = rs.getInt(1);
           // use the generated id
       }