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

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/**
 * 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(JdbcDataContext dataContext,
			Query query, SelectClause selectClause) {
		String result = super.rewriteSelectClause(dataContext, 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(JdbcDataContext strategy, 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(strategy, query, item);
	}
}