如何将以下SQL转换为Linq？

Question

我正在使用IQueryable<T>接口。

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

事情是这样的：

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，它可以帮助你的SQL查询转换为LINQ。当然，对于这种简单的情况来说，这太过于夸张，但如果你更熟悉SQL，那么你可以考虑它的重要查询。

你可以在这里找到它LINQER。

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，如果LINQ将评估DateTime.Now所以我只是把它扔到提前时间的变量。

Answer 4

我pefer以下语法，但你可以使用查询语法，以及：

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();