code: public int update(String sql, Object[] params) throws SQLException {
          Connection conn = this.prepareConnection();
  
          try {
              return this.update(conn, sql, params);
          } finally {
              close(conn);
          }
      }
docs: Executes the given INSERT, UPDATE, or DELETE SQL statement.  The
  <code>Connection</code> is retrieved from the <code>DataSource</code>
  set in the constructor.  This <code>Connection</code> must be in
  auto-commit mode or the update will not be saved.
  
  @param sql The SQL statement to execute.
  @param params Initializes the PreparedStatement's IN (i.e. '?')
  parameters.
  @throws java.sql.SQLException if a database access error occurs
  @return The number of rows updated.