code: private void setUniqueWhere(Where<Extensions, Void> where,
  			String extensionName, boolean queryTableName, String tableName,
  			boolean queryColumnName, String columnName) throws SQLException {
  
  		where.eq(Extensions.COLUMN_EXTENSION_NAME, extensionName);
  
  		if (queryTableName) {
  			if (tableName == null) {
  				where.and().isNull(Extensions.COLUMN_TABLE_NAME);
  			} else {
  				where.and().eq(Extensions.COLUMN_TABLE_NAME, tableName);
  			}
  		}
  
  		if (queryColumnName) {
  			if (columnName == null) {
  				where.and().isNull(Extensions.COLUMN_COLUMN_NAME);
  			} else {
  				where.and().eq(Extensions.COLUMN_COLUMN_NAME, columnName);
  			}
  		}
  
  	}
docs: Set the unique column criteria in the where clause
  
  @param where
  where clause
  @param extensionName
  extension name
  @param queryTableName
  query table name
  @param tableName
  table name
  @param queryColumnName
  query column name
  @param columnName
  column name
  @throws SQLException