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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
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package org.apache.cayenne.dba.oracle;
import java.sql.PreparedStatement;
import org.apache.cayenne.access.QueryLogger;
import org.apache.cayenne.access.trans.SelectTranslator;
import org.apache.cayenne.query.QueryMetadata;
/**
* Select translator that implements Oracle-specific optimizations.
*
*/
class OracleSelectTranslator extends SelectTranslator {
@Override
protected void appendLimitAndOffsetClauses(StringBuilder buffer) {
QueryMetadata metadata = getQuery().getMetaData(getEntityResolver());
int offset = metadata.getFetchOffset();
int limit = metadata.getFetchLimit();
if (limit > 0 || offset > 0) {
int max = (limit <= 0) ? Integer.MAX_VALUE : limit + offset;
buffer.insert(0, "select * from ( select tid.*, ROWNUM rnum from (");
buffer
.append(") tid where ROWNUM <=")
.append(max)
.append(") where rnum > ")
.append(offset);
}
}
/**
* Translates internal query into PreparedStatement, applying Oracle optimizations if
* possible.
*/
@Override
public PreparedStatement createStatement() throws Exception {
String sqlStr = createSqlString();
QueryLogger.logQuery(sqlStr, values);
PreparedStatement stmt = connection.prepareStatement(sqlStr);
initStatement(stmt);
return stmt;
}
}