//$Id: SQLServerDialect.java 11304 2007-03-19 22:06:45Z [email protected] $
package org.hibernate.dialect;
import java.sql.Types;
import org.hibernate.Hibernate;
import org.hibernate.LockMode;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.dialect.function.AnsiTrimEmulationFunction;
/**
* A dialect for Microsoft SQL Server 2000 and 2005
*
* @author Gavin King
*/
public class SQLServerDialect extends SybaseDialect {
public SQLServerDialect() {
registerColumnType( Types.VARBINARY, "image" );
registerColumnType( Types.VARBINARY, 8000, "varbinary($l)" );
registerFunction( "second", new SQLFunctionTemplate(Hibernate.INTEGER, "datepart(second, ?1)") );
registerFunction( "minute", new SQLFunctionTemplate(Hibernate.INTEGER, "datepart(minute, ?1)") );
registerFunction( "hour", new SQLFunctionTemplate(Hibernate.INTEGER, "datepart(hour, ?1)") );
registerFunction( "locate", new StandardSQLFunction("charindex", Hibernate.INTEGER) );
registerFunction( "extract", new SQLFunctionTemplate( Hibernate.INTEGER, "datepart(?1, ?3)" ) );
registerFunction( "mod", new SQLFunctionTemplate( Hibernate.INTEGER, "?1 % ?2" ) );
registerFunction( "bit_length", new SQLFunctionTemplate( Hibernate.INTEGER, "datalength(?1) * 8" ) );
registerFunction( "trim", new AnsiTrimEmulationFunction() );
registerKeyword("top");
}
public String getNoColumnsInsertString() {
return "default values";
}
static int getAfterSelectInsertPoint(String sql) {
int selectIndex = sql.toLowerCase().indexOf( "select" );
final int selectDistinctIndex = sql.toLowerCase().indexOf( "select distinct" );
return selectIndex + ( selectDistinctIndex == selectIndex ? 15 : 6 );
}
public String getLimitString(String querySelect, int offset, int limit) {
if ( offset > 0 ) {
throw new UnsupportedOperationException( "sql server has no offset" );
}
return new StringBuffer( querySelect.length()+8 )
.append(querySelect)
.insert( getAfterSelectInsertPoint(querySelect), " top " + limit )
.toString();
}
/**
* Use <tt>insert table(...) values(...) select SCOPE_IDENTITY()</tt>
*/
public String appendIdentitySelectToInsert(String insertSQL) {
return insertSQL + " select scope_identity()";
}
public boolean supportsLimit() {
return true;
}
public boolean useMaxForLimit() {
return true;
}
public boolean supportsLimitOffset() {
return false;
}
public boolean supportsVariableLimit() {
return false;
}
public char closeQuote() {
return ']';
}
public char openQuote() {
return '[';
}
public String appendLockHint(LockMode mode, String tableName) {
if ( mode.greaterThan( LockMode.READ ) ) {
// does this need holdlock also? : return tableName + " with (updlock, rowlock, holdlock)";
return tableName + " with (updlock, rowlock)";
}
else {
return tableName;
}
}
public String getSelectGUIDString() {
return "select newid()";
}
// The current_timestamp is more accurate, but only known to be supported
// in SQL Server 7.0 and later (i.e., Sybase not known to support it at all)
public String getCurrentTimestampSelectString() {
return "select current_timestamp";
}
// Overridden informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
public boolean areStringComparisonsCaseInsensitive() {
return true;
}
public boolean supportsResultSetPositionQueryMethodsOnForwardOnlyCursor() {
return false;
}
public boolean supportsCircularCascadeDeleteConstraints() {
// SQL Server (at least up through 2005) does not support defining
// cascade delete constraints which can circel back to the mutating
// table
return false;
}
public boolean supportsLobValueChangePropogation() {
// note: at least my local SQL Server 2005 Express shows this not working...
return false;
}
public boolean doesReadCommittedCauseWritersToBlockReaders() {
return false; // here assume SQLServer2005 using snapshot isolation, which does not have this problem
}
public boolean doesRepeatableReadCauseReadersToBlockWriters() {
return false; // here assume SQLServer2005 using snapshot isolation, which does not have this problem
}
}
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