JAVA高级面试进阶训练营视频教程

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一般情况下，使用EF中的查询语法和方法语法可以帮助我们完成绝大部分业务，但是也有特殊的情况需要直接执行Sql语句。比如，我们的业务过于复杂繁琐，或是有些业务使用EF操作时比较复杂，但是使用Sql时会很简单等等。

今天做项目的时候，就由于使用EF来处理逻辑时格外棘手，最终选择了直接执行Sql语句，下面说说具体的业务。

一共关系到三张表，分别是Operators(运营商表)，Orders(订单表)和DeviceCoinsRecords(设备投币记录表)，相应表的定义已经截图如下，就不在这里编写代码了。Operators里放运营商的数据信息，Orders是手机端扫码下单时产生的订单数据，DeviceCoinsRecords是向机器设备投币时产生的数据。

用下面的一张图解释一下：

下面是三张表的结构：

三张表之间的关联关系是：Orders和和DeviceCoinsRecords通过OperatorId关联Operators表的Id主键。

要实现的业务是：

Sql语句表达：

SELECT ROW_NUMBER() OVER(ORDER BY Id ) AS RowId,Id,Name,AllocateRatio,
(SELECT SUM(PayFee) FROM dbo.Orders WHERE Status NOT IN(0,3,4) AND OperatorID=dbo.Operators.Id  AND YEAR(OrderDate)=@Year1 AND MONTH(OrderDate)=@Month1) AS TotalScanCode,
(SELECT SUM(TheDayMoney) FROM dbo.DeviceCoinsRecords WHERE dbo.DeviceCoinsRecords.OperatorID=dbo.Operators.Id AND Year=@Year2 AND Month=@Month2) AS TotalCoinsCast
 FROM dbo.Operators

视图表达：

自然语言表达：

汇总运营商的年度和月度报表，也可选择具体的运营商和年月进行汇总。

一开始我是拒绝在EF中使用SQL查询的，但是花了好长时间，实在是找不到可以替代以上sql的linq语句或者Lambda方法语法，有哪位能写出来的，欢迎挑战一下，但是写出来的很复杂的话，也没这个必要了。

下面说说具体的实现【首先要声明的是我使用的是ABP框架】。

1.在核心层（Core层）的IRepositories文件下创建一个接口IOperatorReportRepository

2.该接口的定义如下代码所示：

  public interface IOperatorReportRepository:IRepository<Operators>
    {
        Task<IEnumerable<OperatorYearOrMonthReport>> QueryMonthReports(int year, int month, int operatorId);
        Task<IEnumerable<OperatorYearOrMonthReport>> QueryYearReports(int year, int operatorId);
    }

3.实现接口代码：

 public class OperatorReportReposiroty:ChargeStationRepositoryBase<Operators>,IOperatorReportRepository
    {
        public OperatorReportReposiroty(IDbContextProvider<ChargeStationDbContext> dbContextProvider)
            : base(dbContextProvider)
        {
            
        }
        public async Task<IEnumerable<OperatorYearOrMonthReport>> QueryMonthReports(int year, int month,int operatorId=0)
        {
            string whereClause = string.Empty;
            if (operatorId>0)
            {
                whereClause += string.Format(" where Id={0} ",operatorId);
            }
            string sql = string.Format(@"
SELECT ROW_NUMBER() OVER(ORDER BY Id ) AS RowId,Id,Name,AllocateRatio,
(SELECT SUM(PayFee) FROM dbo.Orders WHERE Status NOT IN(0,3,4) AND OperatorID=dbo.Operators.Id  AND YEAR(OrderDate)=@Year1 AND MONTH(OrderDate)=@Month1) AS TotalScanCode,
(SELECT SUM(TheDayMoney) FROM dbo.DeviceCoinsRecords WHERE dbo.DeviceCoinsRecords.OperatorID=dbo.Operators.Id AND Year=@Year2 AND Month=@Month2) AS TotalCoinsCast
 FROM dbo.Operators {0}", whereClause);
            return await Context.Database.SqlQuery<OperatorYearOrMonthReport>(sql, 
                new SqlParameter("@Year1", year), 
                new SqlParameter("@Month1", month),
                new SqlParameter("@Year2", year), 
                new SqlParameter("@Month2", month)).ToListAsync();

        }


        public async Task<IEnumerable<OperatorYearOrMonthReport>> QueryYearReports(int year, int operatorId = 0)
        {
            string whereClause = string.Empty;
            if (operatorId>0)
            {
                whereClause += string.Format(" where Id={0} ", operatorId);
            }
            string sql = string.Format(@"
SELECT ROW_NUMBER() OVER(ORDER BY Id )AS RowId,Id,Name,AllocateRatio,
(SELECT SUM(PayFee) FROM dbo.Orders WHERE Status NOT IN(0,3,4) AND OperatorID=dbo.Operators.Id AND YEAR(OrderDate)=@Year3) AS TotalScanCode,
(SELECT SUM(TheDayMoney) FROM dbo.DeviceCoinsRecords WHERE dbo.DeviceCoinsRecords.OperatorID=dbo.Operators.Id AND Year=@Year4) AS TotalCoinsCast
 FROM dbo.Operators {0}", whereClause);
            
            return await Context.Database.SqlQuery<OperatorYearOrMonthReport>(sql, 
                new SqlParameter("@Year3", year),
                new SqlParameter("@Year4", year)).ToListAsync();

        }
    }

这里有点意思的是，如果SqlQuery的后面没有ToList()或者ToListAsync()，那么你会收获一个奇妙的礼物！你可以试试看！

4.在应用服务层调用

  public async Task<PagedResultOutput<GetOperatorReportsOutput>> GetOperatorReports(GetOperatorReportsInput input)
        {
           
            int operatorId = string.IsNullOrEmpty(input.Code)
                ? 0 : _operatorRepository.GetAll().Single(o => o.Code == input.Code).Id;
            IEnumerable<OperatorYearOrMonthReport> operatorMonthReports;
            if (input.Year.HasValue && input.Month.HasValue)
            {
                operatorMonthReports =await _operatorReportRepository.QueryMonthReports(input.Year.Value,input.Month.Value,operatorId);
            }else if (input.Year.HasValue)
            {
                operatorMonthReports =await _operatorReportRepository.QueryYearReports(input.Year.Value,operatorId);
            }
            else
            {
                if (input.IsThisYear)
                {
                    operatorMonthReports = await _operatorReportRepository.QueryYearReports(DateTime.Now.Year,operatorId);
                }
                else
                {
                    operatorMonthReports =await  _operatorReportRepository.QueryMonthReports(DateTime.Now.Year,DateTime.Now.Month,operatorId);
                }
            }
            var totalCount = operatorMonthReports.Count();
            var operatorReportOutputList = operatorMonthReports.MapTo<List<GetOperatorReportsOutput>>();
            return new PagedResultOutput<GetOperatorReportsOutput>(totalCount, operatorReportOutputList);
        }

好了，这次主要记录一下在EF中如何直接调用Sql语句的用法，以后有机会再说说关于在EF中存储过程（包括输出参数的情况）的调用。