Question

我想在LINQ中使用IN运算符。我有一个SQL查询，如下所示。我如何包含where标准。

SQL查询

SELECT     ServiceId, ServiceName, Rate
FROM         Service
WHERE     (ServiceId IN (1, 2, 3, 4))

LINQ

string serviceId = "(1,2,3,4,5,6)";

try
{
    using (var context = new DBEntities())
    {
        var query = (from c in context.Service
                     where c.ServiceId == serviceIds     //ServiceId is the primary key
                     select new
                     {
                        serviceId = c.ServiceId,
                        serviceName = c.ServiceName,
                        rate = c.Rate

                     }).ToList();

        GridView1.DataSource = query.ToList();
        GridView1.DataBind();

    }
}
catch (Exception ex)
{
    throw ex;
}

Answer 1

您可以使用列表的包含，使serviceId成为列表或数组

var serviceIds = new int[] { 1, 2, 3, 4, 5, 6 };

try
{
    using (var context = new DBEntities())
    {
        var query = (from c in context.Service
                        where serviceIds.Contains(c.ServiceId)      //ServiceId is the primary key
                        select new
                        {
                            serviceId = c.ServiceId,
                            serviceName = c.ServiceName,
                            rate = c.Rate

                        }).ToList();

        GridView1.DataSource = query.ToList();
        GridView1.DataBind();

    }
}
catch (Exception ex)
{
    throw ex;
}

Answer 2

where serviceId.Contains(c.ServiceId)

Answer 3

我更喜欢使用Any，使用contains时可能会遇到一些问题。

var serviceIds = new int [] {1,2,3,4,5,6};

try
{
    using (var context = new DBEntities())
    {
        var query = (from c in context.Service
                        where serviceIds.Any(t=> t.ID == c.ServiceId)
                        select new
                        {
                            serviceId = c.ServiceId,
                            serviceName = c.ServiceName,
                            rate = c.Rate

                        }).ToList();

        GridView1.DataSource = query.ToList();
        GridView1.DataBind();

    }
}
catch (Exception ex)
{
    throw ex;
}

如何在LINQ中使用SQL IN运算符

3 个答案: