@Override
    public ResultSet getSchemas() throws SQLException {
        // TODO: handle useCatalogs == true and return schema catalog name
        try {
            return connection.createStatement().executeQuery("SELECT name AS TABLE_SCHEM, " + catalogPlaceholder + " AS TABLE_CATALOG FROM system.databases ORDER BY name");
        } catch (Exception e) {
            throw ExceptionUtils.toSqlState(e);
        }
    }
Returns a ResultSet with the following columns:
TABLE_CAT - String - catalog name
TABLE_SCHEM - String - schema name
TABLE_NAME - String - table name
@return - ResultSet with the above columns
@throws SQLException - if an error occurs
jdbc-v2/src/main/java/com/clickhouse/jdbc/metadata/DatabaseMetaDataImpl.java