declare @date datetime;
set @date = '2017-04-11';--实际为星期二
select DatePart(weekday,@date);

#region 程序集 mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
// C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5\mscorlib.dll
#endregion

using System.Runtime.InteropServices;

namespace System
{
    //
    // 摘要:
    //     Specifies the day of the week.
    [ComVisible(true)]
    public enum DayOfWeek
    {
        //
        // 摘要:
        //     Indicates Sunday.
        Sunday = 0,
        //
        // 摘要:
        //     Indicates Monday.
        Monday = 1,
        //
        // 摘要:
        //     Indicates Tuesday.
        Tuesday = 2,
        //
        // 摘要:
        //     Indicates Wednesday.
        Wednesday = 3,
        //
        // 摘要:
        //     Indicates Thursday.
        Thursday = 4,
        //
        // 摘要:
        //     Indicates Friday.
        Friday = 5,
        //
        // 摘要:
        //     Indicates Saturday.
        Saturday = 6
    }
}

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