SQL语句和EF Group by 用法

1，Group by 根据某个字段排序

select Department,count(*) FROM [PPMG].[dbo].[UnConViolation] group by Department

结果如下：

2，Group by与所传参数联合使用

USE PPMG

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

Alter PROCEDURE UnConViolationTimes
    @type nvarchar()
AS
BEGIN
    declare @sql nvarchar()
    if @type is not null
    begin
      set @sql='select '+ @type+' as Name,count(*) as Count FROM [PPMG].[dbo].[UnConViolation] group by '+@type
      print @sql
      exec(@sql)
    end
END
GO

exec UnConViolationTimes 'Department'

结果如下

3，Group by 后台用法

public List<ViolationTimesDto> GetUnConViolationTimes(string type)
        {
            var UnConViolationList = UnConViolationRepository.Query();

            var ttList = UnConViolationList.GroupBy(m => new { m.Department}).Select(m => new ViolationTimesDto()
            {
                Name=m.Key.Department,
                Count=m.Count()
            }).ToList();
            return ttList;
        }        

结果如下