/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.command.dml;
import org.h2.api.Trigger;
import org.h2.command.CommandInterface;
import org.h2.command.Prepared;
import org.h2.engine.Right;
import org.h2.engine.Session;
import org.h2.engine.UndoLogRecord;
import org.h2.expression.Expression;
import org.h2.result.ResultInterface;
import org.h2.result.Row;
import org.h2.result.RowList;
import org.h2.table.PlanItem;
import org.h2.table.Table;
import org.h2.table.TableFilter;
import org.h2.util.StringUtils;
import org.h2.value.Value;
import org.h2.value.ValueNull;
/**
* 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;
}
public int update() {
tableFilter.startQuery(session);
tableFilter.reset();
Table table = tableFilter.getTable();
session.getUser().checkRight(table, Right.DELETE);
table.fire(session, Trigger.DELETE, true);
table.lock(session, true, false);
RowList rows = new RowList(session);
int limitRows = -1;
if (limitExpr != null) {
Value v = limitExpr.getValue(session);
if (v != ValueNull.INSTANCE) {
limitRows = v.getInt();
}
}
try {
setCurrentRowNumber(0);
while (limitRows != 0 && tableFilter.next()) {
setCurrentRowNumber(rows.size() + 1);
if (condition == null || Boolean.TRUE.equals(condition.getBooleanValue(session))) {
Row row = tableFilter.get();
boolean done = false;
if (table.fireRow()) {
done = table.fireBeforeRow(session, row, null);
}
if (!done) {
rows.add(row);
if (limitRows >= 0 && rows.size() >= limitRows) {
break;
}
}
}
}
int rowScanCount = 0;
for (rows.reset(); rows.hasNext();) {
if ((++rowScanCount & 127) == 0) {
checkCanceled();
}
Row row = rows.next();
table.removeRow(session, row);
session.log(table, UndoLogRecord.DELETE, row);
}
if (table.fireRow()) {
int count = 0;
for (rows.reset(); rows.hasNext();) {
Row row = rows.next();
table.fireAfterRow(session, row, null, false);
count++;
}
}
table.fire(session, Trigger.DELETE, false);
return rows.size();
} finally {
rows.close();
}
}
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();
}
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();
}
public boolean isTransactional() {
return true;
}
public ResultInterface queryMeta() {
return null;
}
public int getType() {
return CommandInterface.DELETE;
}
public void setLimit(Expression limit) {
this.limitExpr = limit;
}
public boolean isCacheable() {
return true;
}
}