com.spun.util.database.ReverseOrderLimitQueryWriter Maven / Gradle / Ivy
/*
* Created on Mar 25, 2004
*
* To change the template for this generated file go to
* Window - Preferences - Java - Code Generation - Code and Comments
*/
package com.spun.util.database;
import com.spun.util.database.SQLQuery.FromPart;
import com.spun.util.database.SQLQuery.LimitPart;
import com.spun.util.database.SQLQuery.OrderByPart;
import com.spun.util.servlets.ValidationError;
/**
* @author Llewellyn Falco
*
* To change the template for this generated type comment go to
* Window - Preferences - Java - Code Generation - Code and Comments
*/
public class ReverseOrderLimitQueryWriter implements SQLQueryWriter
{
private int databaseType;
public ReverseOrderLimitQueryWriter(int databaseType)
{
this.databaseType = databaseType;
}
public String toString(SQLQuery query)
{
assertQueryValid(query);
query.setOrderReversed(true);
String innerQuery = constructInnerQuery(query).toString(databaseType);
String outerQuery = constructOuterQuery(innerQuery, query).toString(databaseType);
return outerQuery;
}
private SQLQuery constructOuterQuery(String innerQuery, SQLQuery query)
{
SQLQuery outer = new SQLQuery(query.getAliasCount());
// add the from parts
Replacer replacer = new Replacer(query.getFromParts().length);
FromPart[] fromParts = query.getFromParts();
for (int i = 0; i < fromParts.length; i++)
{
outer.addFromPart(new FromPart(replacer.replace(fromParts[i].part), fromParts[i].isJoin));
}
String alias = outer.addFrom("(" + innerQuery + ")");
String pkeyColumn = "." + query.getLimitPart().mainTablePkeyColumn;
outer.addWhere(alias + pkeyColumn + " = " + replacer.replace(query.getLimitPart().mainTableAlias) + pkeyColumn,
true);
OrderByPart[] orderByParts = query.getOrderByParts();
for (int i = 0; i < orderByParts.length; i++)
{
outer.addOrderBy(replacer.replace(orderByParts[i].part), !orderByParts[i].ascending);
}
String[] selects = query.getSelectParts();
for (int i = 0; i < selects.length; i++)
{
outer.addSelect(replacer.replace(selects[i]));
}
outer.setLimitPart(new LimitPart(0, query.getLimitPart().numberOfRowsDesired,
query.getLimitPart().mainTableAlias, query.getLimitPart().mainTablePkeyColumn));
return outer;
}
private SQLQuery constructInnerQuery(SQLQuery query)
{
SQLQuery inner = new SQLQuery();
// add the from parts
FromPart[] fromParts = query.getFromParts();
for (int i = 0; i < fromParts.length; i++)
{
inner.addFromPart(fromParts[i]);
}
SQLWhere wherePart = query.getWherePart();
inner.addWhere(wherePart);
OrderByPart[] orderByParts = query.getOrderByParts();
for (int i = 0; i < orderByParts.length; i++)
{
inner.addOrderByPart(orderByParts[i]);
}
inner.addSelect(query.getLimitPart().mainTableAlias + "." + query.getLimitPart().mainTablePkeyColumn + " AS "
+ query.getLimitPart().mainTablePkeyColumn);
inner.setLimitPart(new LimitPart(0,
query.getLimitPart().numberOfRowsDesired + query.getLimitPart().getStartingZeroBasedIndex(),
query.getLimitPart().mainTableAlias, query.getLimitPart().mainTablePkeyColumn));
return inner;
}
private void assertQueryValid(SQLQuery query)
{
String[] assertions = new String[]{"groupByNull", "limitExists", "mainTableValid", "mainTablePkeyValid"};
ValidationError error = new ValidationError(assertions);
error.setError("groupByNull", query.getGroupByParts().length > 0, "Cannot have group by in limit query.");
error.setError("limitExists",
query.getLimitPart() == null || query.getLimitPart().getStartingZeroBasedIndex() == 0,
"Must have a lower limit.");
error.setError("mainTableValid", query.getLimitPart() == null || query.getLimitPart().mainTableAlias == null,
"Must define main table.");
error.setError("mainTablePkeyValid",
query.getLimitPart() == null || query.getLimitPart().mainTablePkeyColumn == null,
"Must define main table pkey column name.");
if (!error.isOk())
{ throw error; }
}
public static class Replacer
{
int index;
public Replacer(int index)
{
this.index = index;
}
public String replace(String string)
{
for (int i = 0; i < index; i++)
{
char letter = (char) ('a' + i);
string = string.replaceAll("\\b" + letter + "\\b", letter + "1");
}
return string;
}
}
}