Question

我写了关于特定员工的搜索查询，但确实没有工作，我知道我的查询中有错误，但现在确实在哪里。我有2个表用于公司，另一个表用于员工信息。进展将是：

1＆＃39; st按部门编号和公司查询公司表中的搜索然后获得PK_companyID。
2＆＃39; ed JOIN公司。PK_companyID==employee.FK_companyID。
3＆＃39; ed查询将在FK_companyID时在员工表中搜索姓名输入在employee table中将相同。

我希望明白

 var query = (from c in db.Company
            where c.departmentNO== departmentNumber && c.companyNo==companyNumber
            join x in db.Employee c.PK_companyID==x.FK_companyID
            where (x.FirstName.Contains(firstName ?? x.FirstName)
            && x.SecondName.Contains(secondName ?? x.SecondName)
            && x.ThirdName.Contains(thirdName ?? x.ThirdName)
            && x.FourthName.Contains(fourthName ?? x.FourthName))
            select x).ToList();

提前感谢。

Answer 1

var query = (from c in db.Company                                        
             join x in db.Employee c.PK_companyID == x.FK_companyID
         where c.departmentNO == departmentNumber && c.companyNo == companyNumber
             && (x.FirstName.Contains(firstName ?? x.FirstName)
                          && x.SecondName.Contains(secondName ?? x.SecondName)
                          && x.ThirdName.Contains(thirdName ?? x.ThirdName)
                          && x.FourthName.Contains(fourthName ?? x.FourthName))

            select x).ToList();

Answer 2

您可以使用下面的代码简化查询和过滤，如果您没有使用所有过滤器，也应该使SQL更清晰。

var employees = (from c in db.Company
            join e in db.Employee on c.PK_companyID equals e.FK_companyID
            where c.departmentNO == departmentNumber && c.companyNo == companyNumber
            select e);

if (!String.IsNullOrEmpty(firstName))
    employees = employees.Where(pr => pr.FirstName.Contains(firstName));

if (!String.IsNullOrEmpty(secondName))
    employees = employees.Where(pr => pr.SecondName.Contains(secondName));

if (!String.IsNullOrEmpty(thirdName))
    employees = employees.Where(pr => pr.ThirdName.Contains(thirdName));

if (!String.IsNullOrEmpty(thirdName))
    employees = employees.Where(pr => pr.FourthName.Contains(fourthName));

return employees.ToList();

Answer 3

你应该使用关键字＆＃34; equals＆＃34;而不是＆＃34; ==＆＃34;在加入如下：

var query = (from c in db.Company                                        
             join x in db.Employee c.PK_companyID equals x.FK_companyID
         where c.departmentNO == departmentNumber && c.companyNo == companyNumber
         .......

希望这会奏效。

asp.net MVC4中的内连接查询

3 个答案: