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HSQLDB - Lightweight 100% Java SQL Database Engine
/* Copyright (c) 2001-2019, The HSQL Development Group
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the HSQL Development Group nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.hsqldb;
import org.hsqldb.error.Error;
import org.hsqldb.error.ErrorCode;
/**
* Implementation of ORDER BY operations
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 2.0.1
* @since 1.9.0
*/
public class ExpressionOrderBy extends Expression {
private boolean isDescending;
private boolean isNullsLast;
ExpressionOrderBy(Expression e) {
super(OpTypes.ORDER_BY);
nodes = new Expression[UNARY];
nodes[LEFT] = e;
collation = e.collation;
e.collation = null;
}
/**
* Set an ORDER BY column expression DESC
*/
void setDescending() {
isDescending = true;
}
/**
* Is an ORDER BY column expression DESC
*/
boolean isDescending() {
return isDescending;
}
/**
* Set an ORDER BY column NULL ordering
*/
void setNullsLast(boolean value) {
isNullsLast = value;
}
/**
* Is an ORDER BY column NULL ordering
*/
boolean isNullsLast() {
return isNullsLast;
}
public Object getValue(Session session) {
return nodes[LEFT].getValue(session);
}
public void resolveTypes(Session session, Expression parent) {
nodes[LEFT].resolveTypes(session, parent);
if (nodes[LEFT].isUnresolvedParam()) {
throw Error.error(ErrorCode.X_42567);
}
dataType = nodes[LEFT].dataType;
if (collation != null && !dataType.isCharacterType()) {
throw Error.error(ErrorCode.X_2H000,
collation.getName().statementName);
}
}
public String getSQL() {
StringBuilder sb = new StringBuilder();
sb.append(Tokens.T_ORDER).append(' ').append(Tokens.T_BY).append(' ');
if (nodes[LEFT].alias != null) {
sb.append(nodes[LEFT].alias.name);
} else {
sb.append(nodes[LEFT].getSQL());
}
if (collation != null) {
sb.append(' ').append(
collation.getName().getSchemaQualifiedStatementName());
}
if (isDescending) {
sb.append(' ').append(Tokens.T_DESC);
}
return sb.toString();
}
protected String describe(Session session, int blanks) {
StringBuilder sb = new StringBuilder();
sb.append(getLeftNode().describe(session, blanks));
if (isDescending) {
for (int i = 0; i < blanks; i++) {
sb.append(' ');
}
sb.append(Tokens.T_DESC).append('\n');
}
return sb.toString();
}
}