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SqlClientDriver.cs
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SqlClientDriver.cs
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using System.Data;
using System.Data.SqlClient;
using NHibernate.AdoNet;
using NHibernate.Dialect;
using NHibernate.Engine;
using NHibernate.SqlCommand;
using NHibernate.SqlTypes;
namespace NHibernate.Driver
{
/// <summary>
/// A NHibernate Driver for using the SqlClient DataProvider
/// </summary>
public class SqlClientDriver : DriverBase, IEmbeddedBatcherFactoryProvider
{
public const int MaxSizeForAnsiClob = 2147483647; // int.MaxValue
public const int MaxSizeForClob = 1073741823; // int.MaxValue / 2
public const int MaxSizeForBlob = 2147483647; // int.MaxValue
public const int MaxSizeForLengthLimitedAnsiString = 8000;
public const int MaxSizeForLengthLimitedString = 4000;
public const int MaxSizeForLengthLimitedBinary = 8000;
public const byte MaxPrecision = 28;
public const byte MaxScale = 5;
public const byte MaxDateTime2 = 8;
public const byte MaxDateTimeOffset = 10;
/// <summary>
/// Creates an uninitialized <see cref="IDbConnection" /> object for
/// the SqlClientDriver.
/// </summary>
/// <value>An unitialized <see cref="System.Data.SqlClient.SqlConnection"/> object.</value>
public override IDbConnection CreateConnection()
{
return new SqlConnection();
}
/// <summary>
/// Creates an uninitialized <see cref="IDbCommand" /> object for
/// the SqlClientDriver.
/// </summary>
/// <value>An unitialized <see cref="System.Data.SqlClient.SqlCommand"/> object.</value>
public override IDbCommand CreateCommand()
{
return new System.Data.SqlClient.SqlCommand();
}
/// <summary>
/// MsSql requires the use of a Named Prefix in the SQL statement.
/// </summary>
/// <remarks>
/// <see langword="true" /> because MsSql uses "<c>@</c>".
/// </remarks>
public override bool UseNamedPrefixInSql
{
get { return true; }
}
/// <summary>
/// MsSql requires the use of a Named Prefix in the Parameter.
/// </summary>
/// <remarks>
/// <see langword="true" /> because MsSql uses "<c>@</c>".
/// </remarks>
public override bool UseNamedPrefixInParameter
{
get { return true; }
}
/// <summary>
/// The Named Prefix for parameters.
/// </summary>
/// <value>
/// Sql Server uses <c>"@"</c>.
/// </value>
public override string NamedPrefix
{
get { return "@"; }
}
/// <summary>
/// The SqlClient driver does NOT support more than 1 open IDataReader
/// with only 1 IDbConnection.
/// </summary>
/// <value><see langword="false" /> - it is not supported.</value>
/// <remarks>
/// MS SQL Server 2000 (and 7) throws an exception when multiple IDataReaders are
/// attempted to be opened. When SQL Server 2005 comes out a new driver will be
/// created for it because SQL Server 2005 is supposed to support it.
/// </remarks>
public override bool SupportsMultipleOpenReaders
{
get { return false; }
}
public override IDbCommand GenerateCommand(CommandType type, SqlString sqlString, SqlType[] parameterTypes)
{
IDbCommand command = base.GenerateCommand(type, sqlString, parameterTypes);
SetParameterSizes(command.Parameters, parameterTypes);
return command;
}
// Used from SqlServerCeDriver as well
public static void SetParameterSizes(IDataParameterCollection parameters, SqlType[] parameterTypes)
{
for (int i = 0; i < parameters.Count; i++)
{
SetVariableLengthParameterSize((IDbDataParameter) parameters[i], parameterTypes[i]);
}
}
protected static void SetVariableLengthParameterSize(IDbDataParameter dbParam, SqlType sqlType)
{
SetDefaultParameterSize(dbParam, sqlType);
// no longer override the defaults using data from SqlType, since LIKE expressions needs larger columns
// https://nhibernate.jira.com/browse/NH-3036
//if (sqlType.LengthDefined && !IsText(dbParam, sqlType) && !IsBlob(dbParam, sqlType))
//{
// dbParam.Size = sqlType.Length;
//}
if (sqlType.PrecisionDefined)
{
dbParam.Precision = sqlType.Precision;
dbParam.Scale = sqlType.Scale;
}
}
protected static void SetDefaultParameterSize(IDbDataParameter dbParam, SqlType sqlType)
{
switch (dbParam.DbType)
{
case DbType.AnsiString:
case DbType.AnsiStringFixedLength:
dbParam.Size = MaxSizeForLengthLimitedAnsiString;
break;
case DbType.Binary:
dbParam.Size = IsBlob(dbParam, sqlType) ? MaxSizeForBlob : MaxSizeForLengthLimitedBinary;
break;
case DbType.Decimal:
dbParam.Precision = MaxPrecision;
dbParam.Scale = MaxScale;
break;
case DbType.String:
case DbType.StringFixedLength:
dbParam.Size = IsText(dbParam, sqlType) ? MaxSizeForClob : MaxSizeForLengthLimitedString;
break;
case DbType.DateTime2:
dbParam.Size = MaxDateTime2;
break;
case DbType.DateTimeOffset:
dbParam.Size = MaxDateTimeOffset;
break;
}
}
/// <summary>
/// Interprets if a parameter is a Clob (for the purposes of setting its default size)
/// </summary>
/// <param name="dbParam">The parameter</param>
/// <param name="sqlType">The <see cref="SqlType" /> of the parameter</param>
/// <returns>True, if the parameter should be interpreted as a Clob, otherwise False</returns>
protected static bool IsText(IDbDataParameter dbParam, SqlType sqlType)
{
return (sqlType is StringClobSqlType) || ((DbType.String == dbParam.DbType || DbType.StringFixedLength == dbParam.DbType) && sqlType.LengthDefined && (sqlType.Length > MaxSizeForLengthLimitedString));
}
/// <summary>
/// Interprets if a parameter is a Blob (for the purposes of setting its default size)
/// </summary>
/// <param name="dbParam">The parameter</param>
/// <param name="sqlType">The <see cref="SqlType" /> of the parameter</param>
/// <returns>True, if the parameter should be interpreted as a Blob, otherwise False</returns>
protected static bool IsBlob(IDbDataParameter dbParam, SqlType sqlType)
{
return (sqlType is BinaryBlobSqlType) || ((DbType.Binary == dbParam.DbType) && sqlType.LengthDefined && (sqlType.Length > MaxSizeForLengthLimitedBinary));
}
#region IEmbeddedBatcherFactoryProvider Members
System.Type IEmbeddedBatcherFactoryProvider.BatcherFactoryClass
{
get { return typeof(SqlClientBatchingBatcherFactory); }
}
#endregion
public override IResultSetsCommand GetResultSetsCommand(ISessionImplementor session)
{
return new BasicResultSetsCommand(session);
}
public override bool SupportsMultipleQueries
{
get { return true; }
}
}
}