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org.eobjects.metamodel.jdbc.dialects.SQLServerQueryRewriter Maven / Gradle / Ivy

/**
 * eobjects.org MetaModel
 * Copyright (C) 2010 eobjects.org
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.eobjects.metamodel.jdbc.dialects;

import org.eobjects.metamodel.jdbc.JdbcDataContext;
import org.eobjects.metamodel.query.FromItem;
import org.eobjects.metamodel.query.Query;
import org.eobjects.metamodel.query.SelectClause;
import org.eobjects.metamodel.schema.Table;

public class SQLServerQueryRewriter extends DefaultQueryRewriter {

    public SQLServerQueryRewriter(JdbcDataContext dataContext) {
        super(dataContext);
    }

    @Override
    public boolean isMaxRowsSupported() {
        return true;
    }

    @Override
    protected String rewriteSelectClause(Query query, SelectClause selectClause) {
        String result = super.rewriteSelectClause(query, selectClause);

        Integer maxRows = query.getMaxRows();
        if (maxRows != null) {
            result = "SELECT TOP " + maxRows + " " + result.substring(7);
        }

        return result;
    }

    @Override
    public String rewriteFromItem(FromItem item) {
        return item.toSql();
    }

    @Override
    protected String rewriteFromItem(Query query, FromItem item) {
        Table table = item.getTable();
        if (table != null) {
            String alias = item.getAlias();
            if (alias == null) {
                // always add an alias in SQL Server
                item.setAlias(table.getName());
            }
        }
        return super.rewriteFromItem(query, item);
    }
}




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