public void updateString(int columnIndex, String x) throws SQLException {
        checkState();

        // To check the type and concurrency of the ResultSet
        // to verify whether updates are possible or not
        checkTypeConcurrency();

        rs.updateString(columnIndex, x);
    }
Updates the designated column with a <code>String</code> value.
The <code>updateXXX</code> methods are used to update column values in the
current row or the insert row.  The <code>updateXXX</code> methods do not
update the underlying database; instead the <code>updateRow</code> or
<code>insertRow</code> methods are called to update the database.

@param columnIndex the first column is 1, the second is 2, and so on
@param x the new column value
@throws SQLException if a database access error occurs
           or this rowset does not currently have a valid connection,
           prepared statement, and result set
src/main/java/org/replicadb/rowset/sun/rowset/JdbcRowSetImpl.java