com.blazebit.persistence.impl.function.pageposition.TransactSQLPagePositionFunction Maven / Gradle / Ivy
/*
* Copyright 2014 - 2020 Blazebit.
*
* 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.blazebit.persistence.impl.function.pageposition;
import com.blazebit.persistence.spi.FunctionRenderContext;
/**
*
* @author Christian Beikov
* @since 1.0.0
*/
public class TransactSQLPagePositionFunction extends PagePositionFunction {
private static final String ROWNUM_FUNCTION = "row_number() over(order by (select 1))";
public TransactSQLPagePositionFunction() {
// Although it is not perfectly safe to rely on this, it works and regarding positional parameters it is also the least hassle
// If we wanted to support this in a "non-dirty" way, we'd have to parse the sql, understand it, and the completely regenerate it
// which is not only an overkill, but apparently also unnecessary
super("(select base1_.rownumber_ from (select " + ROWNUM_FUNCTION
+ " as rownumber_, base_.* from (select top 2147483647 ?1 as base_) as base1_ where ?2 = base1_.?3)");
}
@Override
protected String getRownumFunction() {
return ROWNUM_FUNCTION;
}
@Override
protected void renderPagePosition(FunctionRenderContext functionRenderContext, String idName) {
String subquery = functionRenderContext.getArgument(0);
String subqueryStart = "(select ";
renderer.start(functionRenderContext).addParameter(subquery.substring(subqueryStart.length())).addArgument(1).addParameter(idName).build();
}
}