STRANGE SqlDataReader Behavior

[David Jessee]

I have a SqlDataReader.....

dim dr as SqlDataReader = GetReader;

I want to count the returned records....
dim i as integer
do while dr.read()
i+=1
Loop

I end up 2450 (life is good)

However, if I, instead say
dim i as integer
Dim en ad IEnumerator = DirectCast(dr,IEnumerator)
Do while en.MoveNext()
i+=1
Loop

I end up with 2394

What is up with that? Same SQL statement....no changes in the database.
Its just that when I cast the DataReader into an IEnumerable interface, its
not getting some records

Ideas?

 

[Miha Markic [MVP C#]]

Hi David,

Are you certain that you look at the same data?

 

[William \(Bill\) Vaughn]

One problem might be that if you do a Read to see if there are rows and then
bind to IEnumerator, it might be doing an initial Read--thus throwing away
one row. But that would not account for several missing rows...

--
____________________________________
William (Bill) Vaughn
Author, Mentor, Consultant
Microsoft MVP
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[Miha Markic [MVP C#]]

Isnt' that strange.
IEnumerator thing should do exactly the same...
David: Can you create a sample?

 

[David Jessee]

I'm very sure of it. That was my first thing to check

when read using the IDataReader Interface...I always get the correct number,
verified, by doing a select count(*)
(2450)
when I go through the IEnumerator interface I get a different number 2349,
2433, et (yes, it changes).

 

[Guest]

David,

I tried:

Dim i As Integer
Do While dr.Read
i = i + 1
Loop
MsgBox("Count = " & i)

and

Dim en As IEnumerator = DirectCast(dr, IEnumerable).GetEnumerator
Dim i As Integer
Do While en.MoveNext()
i = i + 1
Loop
MsgBox("Count = " & i)

I got the same result both times on a table with 25 rows.

Did you try both techniques on more than 1 table? Do you get different
results from the 2 techniques on every table?

Kerry Moorman