/*
* 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
* under the License.
*/
package org.apache.empire.db;
import java.util.ArrayList;
import java.util.Set;
import org.apache.empire.db.expr.order.DBOrderByExpr;
/**
* This class is used for building up a partition of a SQL-Command.
* It handles the insert from a specified key word between two DBCommandExpr objects.
* <P>
*
*
*/
public class DBCombinedCmd extends DBCommandExpr
{
// Members
protected DBCommandExpr left;
protected DBCommandExpr right;
protected String keyWord;
/**
* Constructs a new DBFuncExpr object and
* sets the specified parameters to this object.
*
* @param left the first DBCommandExpr object
* @param keyWord the key word between the two DBCommandExpr objects
* @param right the second DBCommandExpr object
*/
public DBCombinedCmd(DBCommandExpr left, String keyWord, DBCommandExpr right)
{
this.left = left;
this.right = right;
this.keyWord = keyWord;
}
@Override
public boolean isValid()
{
return (left.isValid() && right.isValid());
}
/**
* Returns the current DBDatabase object.
*
* @return the current DBDatabase object
*/
@Override
public DBDatabase getDatabase()
{
return left.getDatabase();
}
/**
* @see org.apache.empire.db.DBExpr#addReferencedColumns(Set)
*/
@Override
public void addReferencedColumns(Set<DBColumn> list)
{
left .addReferencedColumns(list);
right.addReferencedColumns(list);
}
/**
* Calls the method dbDBCommandExpr.getSelectExprList from the private variable 'left'.
* Returns a array of all DBColumnExpr object of the Vector: 'select'.
*
* @see org.apache.empire.db.DBCommandExpr#getSelectExprList()
* @return returns an array of all DBColumnExpr object of the Vector: 'select'
*/
@Override
public DBColumnExpr[] getSelectExprList()
{
// DebugMsg(2, "Check: getSelectExprList() for DBCombinedCmd");
return left.getSelectExprList();
}
/**
* Creates the SQL-Command.
*
* @param buf the SQL-Command
* @return true if the creation was successful
*/
@Override
public boolean getSelect(StringBuilder buf)
{
// the left part
left.clearOrderBy();
if (!left.getSelect(buf))
return error(left);
// concat keyword
buf.append( " " );
buf.append( keyWord );
buf.append( " (" );
// the right part
right.clearOrderBy();
if (!right.getSelect(buf))
return error(right);
// done
buf.append( ")" );
// Add optional Order by statement
if ( orderBy!=null )
{ // Having
buf.append("\r\nORDER BY ");
addListExpr(buf, orderBy, CTX_DEFAULT, ", ");
}
return success();
}
@Override
public void orderBy(DBOrderByExpr... exprs)
{
if (orderBy == null)
orderBy = new ArrayList<DBOrderByExpr>();
// Add order by expression
for (DBOrderByExpr obe : exprs)
{
DBColumnExpr c = getCmdColumn(obe.expr);
orderBy.add(new DBOrderByExpr(c, obe.desc));
}
}
}