org.jooq.impl.Limit Maven / Gradle / Ivy
/**
* Copyright (c) 2009-2016, Data Geekery GmbH (http://www.datageekery.com)
* All rights reserved.
*
* 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
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* http://www.apache.org/licenses/LICENSE-2.0
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* 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.
*
* Other licenses:
* -----------------------------------------------------------------------------
* Commercial licenses for this work are available. These replace the above
* ASL 2.0 and offer limited warranties, support, maintenance, and commercial
* database integrations.
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* For more information, please visit: http://www.jooq.org/licenses
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package org.jooq.impl;
import static org.jooq.RenderContext.CastMode.NEVER;
import static org.jooq.conf.ParamType.INLINED;
import static org.jooq.impl.DSL.inline;
import static org.jooq.impl.DSL.one;
import static org.jooq.impl.DSL.val;
import static org.jooq.impl.DSL.zero;
import org.jooq.Clause;
import org.jooq.Context;
import org.jooq.Field;
import org.jooq.Param;
import org.jooq.RenderContext.CastMode;
import org.jooq.conf.ParamType;
import org.jooq.exception.DataAccessException;
/**
* @author Lukas Eder
*/
final class Limit extends AbstractQueryPart {
/**
* Generated UID
*/
private static final long serialVersionUID = 2053741242981425602L;
private static final Field ZERO = zero();
private static final Field ONE = one();
private Field numberOfRows;
private Field numberOfRowsOrMax = DSL.inline(Integer.MAX_VALUE);
private Field offset;
private Field offsetOrZero = ZERO;
private Field offsetPlusOne = ONE;
private boolean rendersParams;
@Override
public final void accept(Context context) {
ParamType paramType = context.paramType();
CastMode castMode = context.castMode();
switch (context.dialect()) {
// True LIMIT / OFFSET support provided by the following dialects
// -----------------------------------------------------------------
// [#4785] OFFSET cannot be without LIMIT
case H2:
case MARIADB:
case MYSQL:
case SQLITE: {
context.castMode(NEVER)
.formatSeparator()
.keyword("limit")
.sql(' ').visit(numberOfRowsOrMax);
if (!offsetZero())
context.formatSeparator()
.keyword("offset")
.sql(' ').visit(offsetOrZero);
context.castMode(castMode);
break;
}
// [#4785] OFFSET can be without LIMIT
case HSQLDB:
case POSTGRES:
case POSTGRES_9_3:
case POSTGRES_9_4:
case POSTGRES_9_5: {
context.castMode(NEVER);
if (!limitZero())
context.formatSeparator()
.keyword("limit")
.sql(' ').visit(numberOfRows);
if (!offsetZero())
context.formatSeparator()
.keyword("offset")
.sql(' ').visit(offsetOrZero);
context.castMode(castMode);
break;
}
// LIMIT [offset], [limit] supported by CUBRID
// -------------------------------------------
case CUBRID: {
context.castMode(NEVER)
.formatSeparator()
.keyword("limit")
.sql(' ').visit(offsetOrZero)
.sql(", ").visit(numberOfRowsOrMax)
.castMode(castMode);
break;
}
// ROWS .. TO ..
// -------------
case FIREBIRD:
case FIREBIRD_2_5:
case FIREBIRD_3_0: {
context.castMode(NEVER)
.formatSeparator()
.keyword("rows")
.sql(' ').visit(getLowerRownum().add(inline(1, SQLDataType.INTEGER)))
.sql(' ').keyword("to")
.sql(' ').visit(getUpperRownum())
.castMode(castMode);
break;
}
case DERBY: {
// Casts are not supported here...
context.castMode(NEVER)
.formatSeparator()
.keyword("offset")
.sql(' ').visit(offsetOrZero)
.sql(' ').keyword("rows");
if (!limitZero())
context.sql(' ').keyword("fetch next")
.sql(' ').visit(numberOfRows)
.sql(' ').keyword("rows only");
context.castMode(castMode);
break;
}
// A default implementation is necessary for hashCode() and toString()
default: {
context.castMode(NEVER)
.formatSeparator()
.keyword("limit")
.sql(' ').visit(numberOfRows);
if (!offsetZero())
context.sql(' ').keyword("offset")
.sql(' ').visit(offsetOrZero);
context.castMode(castMode);
break;
}
}
}
@Override
public final Clause[] clauses(Context ctx) {
return null;
}
/**
* Whether this limit has an offset of zero
*/
final boolean limitZero() {
return numberOfRows == null;
}
/**
* Whether this limit has an offset of zero
*/
final boolean offsetZero() {
return offset == null;
}
/**
* The lower bound, such that ROW_NUMBER() > getLowerRownum()
*/
final Field getLowerRownum() {
return offsetOrZero;
}
/**
* The upper bound, such that ROW_NUMBER() <= getUpperRownum()
*/
final Field getUpperRownum() {
return offsetOrZero.add(numberOfRowsOrMax);
}
/**
* Whether this LIMIT clause is applicable. If false, then no
* LIMIT clause should be rendered.
*/
final boolean isApplicable() {
return offset != null || numberOfRows != null;
}
/**
* Whether this LIMIT clause renders {@link Param} objects. This indicates
* to the SELECT statement, that it may need to prefer
* ROW_NUMBER() filtering over a TOP clause to
* allow for named parameters in the query, as the TOP clause
* may not accept bind variables.
*/
final boolean rendersParams() {
return rendersParams;
}
final void setOffset(int offset) {
if (offset != 0) {
this.offset = val(offset, SQLDataType.INTEGER);
this.offsetOrZero = this.offset;
this.offsetPlusOne = val(offset + 1, SQLDataType.INTEGER);
}
}
final void setOffset(Param offset) {
this.offset = offset;
this.offsetOrZero = offset;
this.rendersParams = true;
}
final void setNumberOfRows(int numberOfRows) {
this.numberOfRows = val(numberOfRows, SQLDataType.INTEGER);
this.numberOfRowsOrMax = this.numberOfRows;
}
final void setNumberOfRows(Param numberOfRows) {
this.numberOfRows = numberOfRows;
this.numberOfRowsOrMax = numberOfRows;
this.rendersParams = true;
}
}