/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* 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 distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.dialect;
import java.sql.Types;
import org.hibernate.dialect.function.NoArgSQLFunction;
import org.hibernate.type.StandardBasicTypes;
/**
* A dialect for Microsoft SQL 2005. (HHH-3936 fix)
*
* @author Yoryos Valotasios
*/
public class SQLServer2005Dialect extends SQLServerDialect {
private static final String SELECT = "select";
private static final String FROM = "from";
private static final String DISTINCT = "distinct";
private static final int MAX_LENGTH = 8000;
public SQLServer2005Dialect() {
// HHH-3965 fix
// As per http://www.sql-server-helper.com/faq/sql-server-2005-varchar-max-p01.aspx
// use varchar(max) and varbinary(max) instead of TEXT and IMAGE types
registerColumnType( Types.BLOB, "varbinary(MAX)" );
registerColumnType( Types.VARBINARY, "varbinary(MAX)" );
registerColumnType( Types.VARBINARY, MAX_LENGTH, "varbinary($l)" );
registerColumnType( Types.LONGVARBINARY, "varbinary(MAX)" );
registerColumnType( Types.CLOB, "varchar(MAX)" );
registerColumnType( Types.LONGVARCHAR, "varchar(MAX)" );
registerColumnType( Types.VARCHAR, "varchar(MAX)" );
registerColumnType( Types.VARCHAR, MAX_LENGTH, "varchar($l)" );
registerColumnType( Types.BIGINT, "bigint" );
registerColumnType( Types.BIT, "bit" );
registerColumnType( Types.BOOLEAN, "bit" );
registerFunction( "row_number", new NoArgSQLFunction( "row_number", StandardBasicTypes.INTEGER, true ) );
}
@Override
public boolean supportsLimitOffset() {
return true;
}
@Override
public boolean bindLimitParametersFirst() {
return false;
}
@Override
public boolean supportsVariableLimit() {
return true;
}
@Override
public int convertToFirstRowValue(int zeroBasedFirstResult) {
// Our dialect paginated results aren't zero based. The first row should get the number 1 and so on
return zeroBasedFirstResult + 1;
}
@Override
public String getLimitString(String query, int offset, int limit) {
// We transform the query to one with an offset and limit if we have an offset and limit to bind
if (offset > 1 || limit > 1) return getLimitString(query, true);
return query;
}
/**
* Add a LIMIT clause to the given SQL SELECT (HHH-2655: ROW_NUMBER for Paging)
*
* The LIMIT SQL will look like:
*
* <pre>
* WITH query AS (
* SELECT ROW_NUMBER() OVER (ORDER BY orderby) as __hibernate_row_nr__,
* original_query_without_orderby
* )
* SELECT * FROM query WHERE __hibernate_row_nr__ BEETWIN offset AND offset + last
* </pre>
*
*
* @param querySqlString
* The SQL statement to base the limit query off of.
* @param offset
* Offset of the first row to be returned by the query (zero-based)
* @param limit
* Maximum number of rows to be returned by the query
*
* @return A new SQL statement with the LIMIT clause applied.
*/
@Override
public String getLimitString(String querySqlString, boolean hasOffset) {
StringBuilder sb = new StringBuilder(querySqlString.trim().toLowerCase());
int orderByIndex = sb.indexOf("order by");
CharSequence orderby = orderByIndex > 0 ? sb.subSequence(orderByIndex, sb.length())
: "ORDER BY CURRENT_TIMESTAMP";
// Delete the order by clause at the end of the query
if (orderByIndex > 0) {
sb.delete(orderByIndex, orderByIndex + orderby.length());
}
// HHH-5715 bug fix
replaceDistinctWithGroupBy(sb);
insertRowNumberFunction(sb, orderby);
// Wrap the query within a with statement:
sb.insert(0, "WITH query AS (").append(") SELECT * FROM query ");
sb.append("WHERE __hibernate_row_nr__ >= ? AND __hibernate_row_nr__ < ?");
return sb.toString();
}
/**
* Utility method that checks if the given sql query is a select distinct one and if so replaces the distinct select
* with an equivalent simple select with a group by clause. See
* {@link SQLServer2005DialectTestCase#testReplaceDistinctWithGroupBy()}
*
* @param sql an sql query
*/
protected static void replaceDistinctWithGroupBy(StringBuilder sql) {
int distinctIndex = sql.indexOf(DISTINCT);
if (distinctIndex > 0) {
sql.delete(distinctIndex, distinctIndex + DISTINCT.length() + 1);
sql.append(" group by").append(getSelectFieldsWithoutAliases(sql));
}
}
/**
* This utility method searches the given sql query for the fields of the select statement and returns them without
* the aliases. See {@link SQLServer2005DialectTestCase#testGetSelectFieldsWithoutAliases()}
*
* @param an
* sql query
* @return the fields of the select statement without their alias
*/
protected static CharSequence getSelectFieldsWithoutAliases(StringBuilder sql) {
String select = sql.substring(sql.indexOf(SELECT) + SELECT.length(), sql.indexOf(FROM));
// Strip the as clauses
return stripAliases(select);
}
/**
* Utility method that strips the aliases. See {@link SQLServer2005DialectTestCase#testStripAliases()}
*
* @param a
* string to replace the as statements
* @return a string without the as statements
*/
protected static String stripAliases(String str) {
return str.replaceAll("\\sas[^,]+(,?)", "$1");
}
/**
* Right after the select statement of a given query we must place the row_number function
*
* @param sql
* the initial sql query without the order by clause
* @param orderby
* the order by clause of the query
*/
protected static void insertRowNumberFunction(StringBuilder sql, CharSequence orderby) {
// Find the end of the select statement
int selectEndIndex = sql.indexOf(SELECT) + SELECT.length();
// Insert after the select statement the row_number() function:
sql.insert(selectEndIndex, " ROW_NUMBER() OVER (" + orderby + ") as __hibernate_row_nr__,");
}
}