What is the most efficient way to query "Is this item in the database? If not, enter it" with LINQ?

Question

I have a collection of strings.  A list of names for example.
I want to loop through them and if the name is not in the DB, add it.  If not, skip it.

I know SQL has something that does kind of what I'm saying.  I'm hoping LINQ has this. 

I thought about doing this:
"Count how many times this name is in the database.  If zero, enter it, otherwise skip", but I am having trouble finding anything explaining even these simple aggregate count queries with LINQ. 

Thanks. :(
 

Answer 1

Hi TecmoTech,

Here is an straight forward way to insert record if it does not exist, else skip:

DbContext dc = new DbContext;
foreach( string name in nameCollection)
{
    if ( !dc.Table.Any( t=>t.Name == name ) ) //record not found, so insert
    {
        //insert logic
    }

}

Hope that helps.

Regards,

---

Syed Mehroz Alam
My Blog | My Articles

Answer 2

Hi TecmoTech,

Here is an straight forward way to insert record if it does not exist, else skip:

DbContext dc = new
 DbContext;

foreach
( string
 name in
 nameCollection)

{

    if
 ( !dc.Table.Any( t=>t.Name == name ) ) //record not found, so insert


    {

        //insert logic


    }



}

Hope that helps.

Regards,

---

Syed Mehroz Alam
My Blog | My Articles

I am not too familiar with the syntax yet, I have created the loop, but I am coding in vb.net.  I can't convert that if statement properly.  Any vb.net guys know how to translate that line?  Thanks!

Answer 3

Here you are, TecmoTech. I used this online tool to convert it to VB.NET

 For Each name As String In nameCollection
     If Not dc.Table.Any(Function(t) t.Name = name) Then
         'record not found, so insert
         'insert logic
        
     End If
 Next

And here are some nice samples in VB.NET for learning LINQ: LINQ To SQL Samples VB

Hope that helps.

Regards,

---

Syed Mehroz Alam
My Blog | My Articles

Answer 4

Thanks Syed, I bookmarked that site.  It will be very helpful in the future!