IF statement inside a LINQ SELECT

linq-to-sql

I'm trying to produce an IF conditional statement inside of a "select new" that checks the values of two fields in order to fill a property.

from e in Employees
where e.EmployeeID == id
select new {
    EmployeeID = e.EmployeeID,
    EmployeeName = e.FirstName + " " + e.LastName,
    Status = (if e.col1.HasValue then "This Value" else if e.col2.HasValue then "Other Value")
}

The columns are nullable and therefore the column types are DateTime? data types.

Only one or the other column will have a datetime value, not both.

How do I go about doing this???

Best Solution

Status = e.col1.HasValue ? "This Value" : (e.col2.HasValue ? "Other Value" : null)

Related Solutions

.net – Entity Framework vs LINQ to SQL

LINQ to SQL only supports 1 to 1 mapping of database tables, views, sprocs and functions available in Microsoft SQL Server. It's a great API to use for quick data access construction to relatively well designed SQL Server databases. LINQ2SQL was first released with C# 3.0 and .Net Framework 3.5.

LINQ to Entities (ADO.Net Entity Framework) is an ORM (Object Relational Mapper) API which allows for a broad definition of object domain models and their relationships to many different ADO.Net data providers. As such, you can mix and match a number of different database vendors, application servers or protocols to design an aggregated mash-up of objects which are constructed from a variety of tables, sources, services, etc. ADO.Net Framework was released with the .Net Framework 3.5 SP1.

This is a good introductory article on MSDN: Introducing LINQ to Relational Data

C# – LINQ to SQL Where Clause Optional Criteria

You can code your original query:

var query = from tags in db.TagsHeaders
                where tags.CST.Equals(this.SelectedCust.CustCode.ToUpper()) 
                && Utility.GetDate(DateTime.Parse(this.txtOrderDateFrom.Text)) <= tags.ORDDTE
                && Utility.GetDate(DateTime.Parse(this.txtOrderDateTo.Text)) >= tags.ORDDTE
                select tags;

And then based on a condition, add additional where constraints.

if(condition)
    query = query.Where(i => i.PONumber == "ABC");

I am not sure how to code this with the query syntax but id does work with a lambda. Also works with query syntax for the initial query and a lambda for the secondary filter.

You can also include an extension method (below) that I coded up a while back to include conditional where statements. (Doesn't work well with the query syntax):

        var query = db.TagsHeaders
            .Where(tags => tags.CST.Equals(this.SelectedCust.CustCode.ToUpper()))
            .Where(tags => Utility.GetDate(DateTime.Parse(this.txtOrderDateFrom.Text)) <= tags.ORDDTE)
            .Where(tags => Utility.GetDate(DateTime.Parse(this.txtOrderDateTo.Text)) >= tags.ORDDTE)
            .WhereIf(condition1, tags => tags.PONumber == "ABC")
            .WhereIf(condition2, tags => tags.XYZ > 123);

The extension method:

public static IQueryable<TSource> WhereIf<TSource>(
    this IQueryable<TSource> source, bool condition,
    Expression<Func<TSource, bool>> predicate)
{
    if (condition)
        return source.Where(predicate);
    else
        return source;
}

Here is the same extension method for IEnumerables:

public static IEnumerable<TSource> WhereIf<TSource>(
    this IEnumerable<TSource> source, bool condition,
    Func<TSource, bool> predicate)
{
    if (condition)
        return source.Where(predicate);
    else
        return source;
}

Best Solution

Related Solutions

.net – Entity Framework vs LINQ to SQL

C# – LINQ to SQL Where Clause Optional Criteria

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