com.xdev.jadoth.sqlengine.internal.interfaces.TableExpression Maven / Gradle / Ivy
/*
* XDEV Application Framework - XDEV Application Framework
* Copyright © 2003 XDEV Software (https://xdev.software)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see TableExpression instance is any object that can resolve to a valid table identifier for
* specifying a certain table in the database.
*
* Not that this is NOT equivalent to the "
" defined in the SQL Standard.
.
*
* @author Thomas Muenz
*/
public interface TableExpression extends Serializable
{
/**
* AS.
*
* @param newAlias the new alias
* @return the table expression
* @throws SQLEngineException the sQL engine exception
*/
public TableExpression AS(String newAlias) throws SQLEngineException;
/**
* The Class TableExpressionUtils.
*/
public static class Utils
{
/*
* To avoid the need for a public getAlias() in SqlTable
*/
/**
* Gets the alias.
*
* @param tableExpression the table expression
* @return the alias
*/
public static String getAlias(final TableExpression tableExpression)
{
if(tableExpression instanceof SqlQualifiedIdentityWithAlias){
return ((SqlQualifiedIdentityWithAlias)tableExpression).sql().alias;
}
else if(tableExpression instanceof SELECT){
return ((SELECT)tableExpression).getAlias();
}
else {
return null;
}
}
/*
* To avoid the need for a public getDatabaseGateway() in SqlTable
*/
/**
* Gets the database gateway.
*
* @param tableExpression the table expression
* @return the database gateway
*/
public static DatabaseGateway getDatabaseGateway(final TableExpression tableExpression)
{
if(tableExpression instanceof SqlTable){
return ((SqlTable)tableExpression).db.getDatabaseGateway();
}
else if(tableExpression instanceof SELECT){
return ((SELECT)tableExpression).getDatabaseGatewayForExecution();
}
else {
return SQL.getDefaultDatabaseGateway();
}
}
/**
* Use with care, as this method swallows ClassCastExceptions.
*
* @param tableExpression
*
* @return tableExpression as an SqlTableIdentity if it is one,
* otherwise null.
*/
public static SqlTableIdentity toSqlTableIdentity(final TableExpression tableExpression)
{
if(tableExpression instanceof SqlTableIdentity){
return (SqlTableIdentity)tableExpression;
}
return null;
}
}
}
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