/// <summary>
/// 返回执行指定Sql语句后返回的结果
/// </summary>
/// <typeparam name="T">数据类型</typeparam>
/// <param name="dbCommand">数据库命令</param>
/// <param name="dataType">数据类型</param>
/// <param name="connection">数据库连接</param>
/// <param name="transaction">数据库事务</param>
/// <returns>返回的结果</returns>
public T ExecuteScalar <T>(DbCommand dbCommand, DataType dataType, DbConnection connection, DbTransaction transaction)
{
if (dbCommand == null)
{
throw new ArgumentNullException("dbCommand");
}
Object obj = this.ExecuteScalar(dbCommand, connection, transaction);
return(DbConvert.IsDBNull(obj) ? default(T) : (T)DbConvert.ToValue(obj, dataType));
}
/// <summary>
/// 将数据库字段按数据类型转换
/// </summary>
/// <param name="obj">原始数据库字段</param>
/// <param name="dataType">数据类型</param>
/// <returns>转换后的内容</returns>
public static Object ToValue(Object obj, DataType dataType)
{
switch (dataType)
{
case DataType.Binary:
return((Byte[])obj);
case DataType.Boolean:
return(DbConvert.ToBoolean(obj));
case DataType.Byte:
return(DbConvert.ToByte(obj));
case DataType.SByte:
return(DbConvert.ToSByte(obj));
case DataType.Int16:
return(DbConvert.ToInt16(obj));
case DataType.Int32:
return(DbConvert.ToInt32(obj));
case DataType.Int64:
return(DbConvert.ToInt64(obj));
case DataType.UInt16:
return(DbConvert.ToUInt16(obj));
case DataType.UInt32:
return(DbConvert.ToUInt32(obj));
case DataType.UInt64:
return(DbConvert.ToUInt64(obj));
case DataType.Single:
return(DbConvert.ToSingle(obj));
case DataType.Double:
return(DbConvert.ToDouble(obj));
case DataType.Currency:
case DataType.Decimal:
case DataType.VarNumeric:
return(DbConvert.ToDecimal(obj));
case DataType.Object:
return(obj);
case DataType.Date:
case DataType.DateTime:
case DataType.DateTime2:
case DataType.Time:
return(DbConvert.ToDateTime(obj));
case DataType.DateTimeOffset:
return(DbConvert.ToDateTimeOffset(obj));
case DataType.Guid:
return(DbConvert.ToGuid(obj));
case DataType.AnsiString:
case DataType.AnsiStringFixedLength:
case DataType.String:
case DataType.StringFixedLength:
case DataType.Xml:
return(DbConvert.ToString(obj));
default:
return(obj);
}
}