org.apache.empire.db.expr.column.DBFuncExpr Maven / Gradle / Ivy
/*
* 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.expr.column;
// Java
import org.apache.empire.data.DataType;
import org.apache.empire.db.DBColumn;
import org.apache.empire.db.DBColumnExpr;
/**
* This class is used for performing various SQL functions on a column or column expression.
*
* There is no need to explicitly create instances of this class.
* Instead use any of the following functions:
* {@link DBColumnExpr#abs() }, {@link DBColumnExpr#coalesce(Object) }, {@link DBColumnExpr#convertTo(DataType) },
* {@link DBColumnExpr#decode(java.util.Map, Object) }, {@link DBColumnExpr#lower() }, {@link DBColumnExpr#min() },
* {@link DBColumnExpr#max() }, {@link DBColumnExpr#month() }, {@link DBColumnExpr#sum() },
* {@link DBColumnExpr#trim() }, {@link DBColumnExpr#upper() }, {@link DBColumnExpr#year() }
*
*
*/
public class DBFuncExpr extends DBAbstractFuncExpr
{
private final static long serialVersionUID = 1L;
protected final int phrase;
protected final Object[] params;
protected String template;
/**
* Constructs a new DBFuncExpr object set the specified parameters to this object.
* Do not use directly - use any of the DBColumnExpr.??? factory functions instead!
*
* The sql function string is built from a string template.
* The template string is identified by the phrase param and obtained from the driver.
*
* @param expr the DBColumnExpr object
* @param phrase the SQL-phrase
* @param params an array of params which will be replaced in the template
* @param updateColumn optional update column if any. This parameter may be null
* @param isAggregate indicates whether the function is an aggregate function (sum, min, max, avg, ...)
* @param dataType indicates the data type of the function result
*/
public DBFuncExpr(DBColumnExpr expr, int phrase, Object[] params, DBColumn updateColumn, boolean isAggregate, DataType dataType)
{
super(expr, updateColumn, isAggregate, dataType);
// Set Phrase and Params
this.phrase = phrase;
this.params = params;
this.template = null;
}
/**
* Constructs a new DBFuncExpr object set the specified parameters to this object.
*
* The sql function string is built from a string template.
* The template string must contain a ? which is a placeholder for the column expression.
*
* @param expr the DBColumnExpr object
* @param template specifies a template for the expression. The template must contain a ? placeholder for the column expression
* @param params an array of params which will be replaced in the template
* @param updateColumn optional update column if any. This parameter may be null
* @param isAggregate indicates whether the function is an aggregate function (sum, min, max, avg, ...)
* @param dataType indicates the data type of the function result
*/
public DBFuncExpr(DBColumnExpr expr, String template, Object[] params, DBColumn updateColumn, boolean isAggregate, DataType dataType)
{
super(expr, updateColumn, isAggregate, dataType);
// Set Phrase and Params
this.phrase = 0;
this.params = params;
this.template = template;
}
@Override
protected String getFunctionName()
{
// Get the template
if (template==null && getDatabaseDriver()!=null)
template = getDatabaseDriver().getSQLPhrase(phrase);
// Get the first word
if (template!=null)
{
String s = template.trim();
int i=0;
for (; i0)
return s.substring(0,i);
}
// default
return "func_" + String.valueOf(phrase);
}
/**
* Creates the SQL-Command adds a function to the SQL-Command.
*
* @param sql the SQL-Command
* @param context the current SQL-Command context
*/
@Override
public void addSQL(StringBuilder sql, long context)
{
// Get the template
if (template==null)
template = getDatabaseDriver().getSQLPhrase(phrase);
// Add SQL
super.addSQL(sql, template, params, context);
}
}