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Efim Mett · Guest

Hi community,

I have encountered the following phenomenon when working with a MS SQL 2005
DB using DBExpress in a VCL.Net application:

Pseudocode:
SELECT Field1, Field2 FROM Table1: ok
First: ok
while not EOF do begin
......
UPDATE Table1 SET Field2=<Value1> Where Field1 = <Value2>
Next
end

UPDATE is executed only if there is no record in the SELECT result with
Field1=<Value2>, i.e. no record is updated.
In the other case applications is blocked, and MS SQL does nothing (as
observered in SQL Profiler).
The same behaviour using BDP.

I feel it can have something to do with Isolation Level, but no success
using BDP. How I can set it with DB Express?
In SQL DB Manager is everything ok.

Any clue?

/Efim

Efim Mett · Guest

I believe I could figure out the problem.

2 conditions are necessary to reproduce the behaviour:
1. SELECT contains at least one Join
2. SELECT contains at least 1 BLOB-field (of subtype image in my case)

I've put a small example in "Attachments" to illustrate the problem with
DBExpress, BDP and native SQL providers.
Whereas BDP and DBExpress point the same behaviour, SQL doesn't allow to run
UPDATE at all with the error message "Update is not possible with an opened
DataReader" (translated from german), no matter how SELECT is built.

/Efim

Efim Mett · Guest

I wonder if nobody could reproduce this behaviour?? Or all are so-o-o busy
Smile

?

/Efim

"Efim Mett" <Efim.Mett@t-online.de> schrieb im Newsbeitrag
news:450a848d (AT) newsgroups (DOT) borland.com...

Efim Mett · Guest

QC #35076

/Efim