public Blob getBlob(String colName) throws SQLException {
        return getBlob(findColumn(colName));
    }
Returns the value of the designated column in the current row
of this rowset's <code>ResultSet</code> object as a <code>Blob</code> object.

@param colName the name of the column from which to retrieve the value
@return a <code>Blob</code> object representing the SQL <code>BLOB</code>
        value in the specified column
@throws SQLException if (1) a database access error occurs
           or (2) this rowset does not currently have a valid connection,
           prepared statement, and result set
src/main/java/org/replicadb/rowset/sun/rowset/JdbcRowSetImpl.java