CODEWITHSUNDEEP
c#entity-frameworklinq
Caverman
Caverman

Reputation: 3707

How many database calls in this EF query?

I'm taking over someone's code and came across this Entity Framework query and I've never seen it done this way. Isn't there a database query every time the .FirstOrDefault is called? So in this case there would be 4 database queries meaning 5 open/close connections to the database? Just trying to understand if this is an ineffective way of doing this which it seems like it to me.

var record = from e in ctx.bio_employee.Where(x => x.emp_id == emp_id)
             select new
             {
                  ta.ta_system
                 ,ta.bio_consent_flag
                 ,e.bio_consentform_rid
             };


if (record.FirstOrDefault() != null) 
{
    vm.TASystem = record.FirstOrDefault().ta_system;
    vm.bio_consent_flag = record.FirstOrDefault().bio_consent_flag == null ? "N" : record.FirstOrDefault().bio_consent_flag.Trim().ToUpper();
    vm.employee_bio_consentform_rid = record.FirstOrDefault().bio_consentform_rid;
}

Upvotes: 2

Views: 177

Answers (1)

David Browne - Microsoft
David Browne - Microsoft

Reputation: 89141

That executes the same query 4 or 5 separate times, although connection pooling will reuse a single connection. Should be

var query = from e in ctx.bio_employee.Where(x => x.emp_id == emp_id)
             select new
             {
                  ta.ta_system
                 ,ta.bio_consent_flag
                 ,e.bio_consentform_rid
             };

var result = query.FirstOrDefault();

if (result != null) 
{
    vm.TASystem = result .ta_system;
    vm.bio_consent_flag = result .bio_consent_flag == null ? "N" : result .bio_consent_flag.Trim().ToUpper();
    vm.employee_bio_consentform_rid = result.bio_consentform_rid;
}

Upvotes: 2

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