Question

我正在使用IQueryable<T>界面。

如何将以下sql语句翻译为IQueryable？

select * from customer
where joindate > DateTime.Now and
      (customertype = 'system' or customerstatus = 'active') and
      customerlocation = 'europe'

Answer 1

这样的事情：

    var result = from record in context.customer 
    where record.joindate > DateTime.Now && 
        (record.customertype == "system" || record.customerstatus == "active") && 
        record.customerlocation == "europe"
    select record

有一个很好的工具，Linqer，它可以帮助您将SQL查询转换为LINQ。当然对于这种简单的情况来说它是矫枉过正的，但如果您对SQL更熟悉，当然可以考虑进行繁重的查询。

您可以在LINQER找到它。

Answer 2

var query = 
from i in db.customer
where i.joindate > DateTime.Now 
&& (i.customertype == 'system' || i.customerstatus == 'active')
&& i.customerlocation == 'europe'
select i;

Answer 3

var now = DateTime.Now;
var queryable = Customers.Where(x=>x.joindate > now && (x.customertype == "system" || x.customerstatus == "active") && x.customerlocation == "europe")

我不记得linq是否会评估DateTime.Now所以我只是提前把它扔进一个变量。

Answer 4

我更喜欢以下语法，但您也会使用查询语法：

var results = yourContext.Customers.Where(c => (c.JoinDate > DateTime.Now) &&
    ((c.CustomerType.Equals("system") || (c.CustomerType.Equals("active")) &&
    (c.CustomerLocation.Equals("europe")));

使用查询语法：

var results = from c in yourContext.Customers
    where (c.JoinDate > DateTime.Now) &&
    (c.CustomerType.Equals("system") || c.CustomerStatus.Equals("active")) &&
    c.CustomerLocation.Equals("europe")
    select c;

Answer 5

var result = (from c in customer
              where (c.joindate > DateTime.Now) &&
                    (c.customertype == "system" || c.customerstatus == "active") &&
                    (c.customerlocation == "europe")
              select c)
             .ToList();

如何将以下SQL转换为Linq？

5 个答案: