protected void getColumnsForUniqueConstraint(
     Connection jdbcConnection, UniqueConstraint constraint, String schema) throws SQLException {
   PreparedStatement stmt = null;
   ResultSet rs = null;
   try {
     stmt =
         jdbcConnection.prepareStatement(
             "select ucc.column_name from all_cons_columns ucc where ucc.constraint_name=? and ucc.owner=? order by ucc.position");
     stmt.setString(1, constraint.getName());
     stmt.setString(2, schema);
     rs = stmt.executeQuery();
     while (rs.next()) {
       String columnName = rs.getString("column_name");
       constraint.getColumns().add(columnName);
     }
   } finally {
     if (rs != null) {
       try {
         rs.close();
       } catch (SQLException ignored) {
       }
     }
     if (stmt != null) stmt.close();
   }
 }
  @Override
  protected void readUniqueConstraints(
      DatabaseSnapshot snapshot, String schema, DatabaseMetaData databaseMetaData)
      throws DatabaseException, SQLException {
    Database database = snapshot.getDatabase();
    updateListeners("Reading unique constraints for " + database.toString() + " ...");
    List<UniqueConstraint> foundUC = new ArrayList<UniqueConstraint>();

    Connection jdbcConnection =
        ((JdbcConnection) database.getConnection()).getUnderlyingConnection();

    PreparedStatement statement = null;
    ResultSet rs = null;

    // Setting default schema name. Needed for correct statement generation
    if (schema == null) schema = database.convertRequestedSchemaToSchema(schema);

    try {
      String query =
          "select uc.constraint_name,uc.table_name,uc.status,uc.deferrable,uc.deferred,ui.tablespace_name from all_constraints uc, all_cons_columns ucc, all_indexes ui where uc.constraint_type='U' and uc.index_name = ui.index_name and uc.constraint_name = ucc.constraint_name and uc.owner = '"
              + schema
              + "' and ui.table_owner = '"
              + schema
              + "' and ucc.owner = '"
              + schema
              + "'";
      statement = jdbcConnection.prepareStatement(query);
      rs = statement.executeQuery();
      while (rs.next()) {
        String constraintName = rs.getString("constraint_name");
        String tableName = rs.getString("table_name");
        String status = rs.getString("status");
        String deferrable = rs.getString("deferrable");
        String deferred = rs.getString("deferred");
        String tablespace = rs.getString("tablespace_name");
        UniqueConstraint constraintInformation = new UniqueConstraint();
        constraintInformation.setName(constraintName);
        constraintInformation.setTablespace(tablespace);
        if (!database.isSystemTable(null, schema, tableName)
            && !database.isLiquibaseTable(tableName)) {
          Table table = snapshot.getTable(tableName);
          if (table == null) {
            continue; // probably different schema
          }
          constraintInformation.setTable(table);
          constraintInformation.setDisabled("DISABLED".equals(status));
          if ("DEFERRABLE".equals(deferrable)) {
            constraintInformation.setDeferrable(true);
            constraintInformation.setInitiallyDeferred("DEFERRED".equals(deferred));
          }
          getColumnsForUniqueConstraint(jdbcConnection, constraintInformation, schema);
          foundUC.add(constraintInformation);
        }
      }
      snapshot.getUniqueConstraints().addAll(foundUC);
    } finally {
      try {
        rs.close();
      } catch (SQLException ignored) {
      }
      if (statement != null) {
        statement.close();
      }
    }
  }