Delete.java

/*
 * Copyright 2014-2015 the original author or authors
 *
 * Licensed under the Apache License, Version 2.0 (the “License”);
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an “AS IS” BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wplatform.ddal.command.dml;

import com.wplatform.ddal.command.CommandInterface;
import com.wplatform.ddal.command.Prepared;
import com.wplatform.ddal.command.expression.Expression;
import com.wplatform.ddal.dbobject.table.PlanItem;
import com.wplatform.ddal.dbobject.table.TableFilter;
import com.wplatform.ddal.engine.Session;
import com.wplatform.ddal.result.ResultInterface;
import com.wplatform.ddal.util.StringUtils;

/**
 * This class represents the statement
 * DELETE
 */
public class Delete extends Prepared {

    private Expression condition;
    private TableFilter tableFilter;

    /**
     * The limit expression as specified in the LIMIT or TOP clause.
     */
    private Expression limitExpr;

    public Delete(Session session) {
        super(session);
    }

    public void setTableFilter(TableFilter tableFilter) {
        this.tableFilter = tableFilter;
    }

    public void setCondition(Expression condition) {
        this.condition = condition;
    }

    @Override
    public String getPlanSQL() {
        StringBuilder buff = new StringBuilder();
        buff.append("DELETE ");
        buff.append("FROM ").append(tableFilter.getPlanSQL(false));
        if (condition != null) {
            buff.append("\nWHERE ").append(StringUtils.unEnclose(
                    condition.getSQL()));
        }
        if (limitExpr != null) {
            buff.append("\nLIMIT (").append(StringUtils.unEnclose(
                    limitExpr.getSQL())).append(')');
        }
        return buff.toString();
    }

    @Override
    public void prepare() {
        if (condition != null) {
            condition.mapColumns(tableFilter, 0);
            condition = condition.optimize(session);
            condition.createIndexConditions(session, tableFilter);
        }
        PlanItem item = tableFilter.getBestPlanItem(session, 1);
        tableFilter.setPlanItem(item);
        tableFilter.prepare();
    }

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

    @Override
    public ResultInterface queryMeta() {
        return null;
    }

    @Override
    public int getType() {
        return CommandInterface.DELETE;
    }

    public void setLimit(Expression limit) {
        this.limitExpr = limit;
    }

    @Override
    public boolean isCacheable() {
        return true;
    }
    
    // getter
    public Expression getCondition() {
        return condition;
    }

    public TableFilter getTableFilter() {
        return tableFilter;
    }

    public Expression getLimitExpr() {
        return limitExpr;
    }

}