Question

我在这里有以下查询。如何为此sql获取类似的linq查询。

var express = require("express");
var app = express();
var server = app.listen(3000);
// Respond to 'Ctrl+C'
process.on("SIGINT", function () {
  // stop accepting connections
  server.close(function () {
    // connections are closed
    // exit the process
    process.exit(0);
  });
});
// Server is shutting down
process.on("SIGTERM", function () {
  // stop accepting connections
  server.close(function () {
    // connections are closed
    // exit the process
    process.exit(0);
  });
});

我使用了下面的linq翻译，但它在某处失败了。

SELECT * 
FROM PublishedLineBar 
WHERE PublishedRosterShiftId 
IN (SELECT LatestShiftId FROM 
       ( SELECT MAX(PublishedRosterShiftId) as LatestShiftId, DayNumber 
         FROM PublishedRosterShift
         WHERE employeeid = 14454
         GROUP BY DayNumber) 
       as ShiftProjection )

Answer 1

以下是用于SQL IN (...)子句的子查询的LINQ等效项（删除了不必要的嵌套）：

var inner = dbContext.PublishedRosterShifts
    .Where(s => s.EmployeeId == EmployeeId)
    .GroupBy(s => s.DayNumber)
    .Select(g => g.Max(s => s.PublishedRosterShiftId));

和使用它的查询：

var query = from l in dbContext.PublishedLineBars
            where inner.Contains(l.PublishedRosterShiftId)
            select l;

或只是

var query = dbContext.PublishedLineBars
    .Where(l => inner.Contains(l.PublishedRosterShiftId));

您在尝试中缺少的是SQL SELECT MAX(PublishedRosterShiftId) as LatestShiftId, DayNumber对GROUP BY运算符的结果进行操作，因此在LINQ中Select应该在GroupBy之后。

实体框架复杂查询嵌套C＃对象

1 个答案: