Question

假设我有一个公司表，一个Employees表，而Employees表有一个FK列到Companies表。查询公司并返回相关员工非常容易。

var companies = from c in Companies
                select c;

通过添加where子句来过滤这些公司非常容易。但是如何过滤上面查询中返回的员工。例如，仅包括那些Employed列为true的员工？

我想退回所有公司，只有那些目前就业的员工。

Answer 1

检索受雇的公司及其雇员：

var companies = from c in Companies
                select new
                {
                    Company = c,
                    EmployedPersons = c.Employees.Where(e => e.Employed)
                };

像这样使用：

foreach (var company in companies)
{
    Console.WriteLine("{0}", company.Company);
    foreach (var employee in company.EmployedPersons)
    {
        Console.WriteLine("{0}", employee);
    }
}

另一种方法，根据您的评论，您需要在其他地方过滤此内容：

public void DisplayEmployedPersons(Company company)
{
    foreach (var employee in company.Employees.Where(e => e.Employed))
    {
        Console.WriteLine("{0}", employee);
    }
}

最后，您可以修改为Customer数据对象生成的分部类：

public partial class Customer
{
    public IEnumerable<Employee> CurrentEmployees
    {
        get { return this.Employees.Where(e => e.Employed);
    } 
}

Answer 2

我不确定你想对员工做什么，但这是一种迭代它们的方法：

var companies = from c in Companies
                where c.Employees.Any(e => e.Employed)
                select c;

foreach (var company in companies) {
    foreach (var employee in company.Employees.Where(e => e.Employed)) {
        // your employed employees are iterated here
    }
}

Answer 3

使用查询语法：

var companies = from c in Companies
                from e in c.Employees
                where e.Employed
                select c;

在LINQ中过滤相关表

3 个答案: