Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2020 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.fmap.dal.store.jdbc2.spi.operations;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import org.apache.commons.lang3.StringUtils;

import org.gvsig.expressionevaluator.ExpressionBuilder;

import org.gvsig.fmap.dal.exception.DataException;

import org.gvsig.fmap.dal.feature.FeatureType;

import org.gvsig.fmap.dal.store.jdbc2.JDBCHelper;

import org.gvsig.fmap.dal.store.jdbc2.spi.JDBCSQLBuilderBase;

import org.gvsig.fmap.dal.store.jdbc.exception.JDBCSQLException;

import org.gvsig.fmap.dal.store.jdbc2.JDBCUtils;

import org.gvsig.fmap.dal.store.jdbc2.OperationsFactory.TableReference;

import static org.gvsig.fmap.dal.store.jdbc2.spi.JDBCSQLBuilderBase.PROP_TABLE;

public class TableIsEmptyOperation extends AbstractConnectionOperation {

    private final TableReference table;

    private final String baseFilter;

    private final String filter;

    private final FeatureType featureType;

    public TableIsEmptyOperation(

            JDBCHelper helper

        ) {

        this(helper, null, null, null, null);

    }

    public TableIsEmptyOperation(

            JDBCHelper helper,

            FeatureType featureType,

            TableReference table,

            String baseFilter,

            String filter

        ) {

        super(helper);

        this.featureType = featureType;

        this.table = table;

        this.baseFilter = baseFilter;

        this.filter = filter;

    }

    @Override

    public final Object perform(Connection conn) throws DataException {

        return this.tableIsEmpty(conn);

    }

    public String getSQL() {

        JDBCSQLBuilderBase sqlbuilder = this.createSQLBuilder();

        ExpressionBuilder expbuilder = sqlbuilder.expression();

        sqlbuilder.select().column().all();

        sqlbuilder.select().from().table()

                .database(this.table.getDatabase())

                .schema(this.table.getSchema())

                .name(this.table.getTable());

        sqlbuilder.select().from().subquery(this.table.getSubquery());

        if (!StringUtils.isEmpty(baseFilter)) {

            sqlbuilder.select().where().set( expbuilder.custom(baseFilter) );

        }

        if (!StringUtils.isEmpty(filter)) {

            // El and() hace un set() si no hay un filtro previo

            sqlbuilder.select().where().and(expbuilder.toValue(filter));

        }

        sqlbuilder.select().limit(1);

        this.helper.processSpecialFunctions(sqlbuilder, featureType, null);

        sqlbuilder.setProperties(

                ExpressionBuilder.Variable.class,

                PROP_TABLE, table

        );

        String sql = sqlbuilder.select().toString();

        return sql;

    }

    public boolean tableIsEmpty(Connection conn) throws DataException {

        String sql = this.getSQL();

        Statement st = null;

        ResultSet rs = null;

        try {

            st = conn.createStatement();

            rs = JDBCUtils.executeQuery(st, sql);

            return !rs.next();

        } catch (SQLException ex) {

            throw new JDBCSQLException(ex);

        } finally {

            JDBCUtils.closeQuietly(st);

            JDBCUtils.closeQuietly(rs);

        }

    }

}