实体框架中的查询

本文关键字：查询 框架 实体 | 更新日期: 2023-09-27 17:57:58

我必须使用此查询获取前20行，而like子句不起作用。有人能告诉我为什么/帮我找到解决方案吗？

var zipcodes = (from results in db1.ZipCodes1 
                                 where  results.CityType == "D" && results.ZIPCode like '%ZC %'
                                 select new Ajaxresults 
                {
                   ZIPCode= results.ZIPCode,
                   CityName = results.CityName,
                   StateAbbr = results.StateAbbr,
                   StateName = results.StateName
                }).GroupBy(o => o.ZIPCode);

实体框架中的查询

要选择前20行，应使用LINQ Take运算符

var zipcodes = (from results in db1.ZipCodes1
   ...
   ).Take(20);

代码应该是这样的：

var zipcodes = (from results in db1.ZipCodes1 
                where  results.CityType == "D" && results.ZIPCode.Contains("ZC ")
                select new Ajaxresults 
                {
                   ZIPCode= results.ZIPCode,
                   CityName = results.CityName,
                   StateAbbr = results.StateAbbr,
                   StateName = results.StateName
                }).GroupBy(o => o.ZIPCode).Take(20);

String.Contains方法将被转换为相应的SQL LIKE运算符。您可以将查询更改为类似的内容：

var zipcodes = (from results in db1.ZipCodes1 
                             where results.CityType == "D" 
                                && results.ZIPCode.Contains("ZC ")
                             select new Ajaxresults 
            {
               ZIPCode= results.ZIPCode,
               CityName = results.CityName,
               StateAbbr = results.StateAbbr,
               StateName = results.StateName
            }).GroupBy(o => o.ZIPCode);
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