Microsoft Dynamics AX (Archived)

Tablebuffer selectforupdate

(1) Share

Report

Posted on by Pete Alberts

3,542

I have always assumed the following statements are similar and for all practical purposes identical

Tablebuffer tbl;

tbl.selectForUpdate(_forUpdate);

select tbl where {some condition}

Tablebuffer tbl;

select forUpdate tbl where {some condition}

I came across the CompanyImage table find method:

VirtualBox_5F00_Mah-Man-VM_5F00_04_5F00_05_5F00_2018_5F00_08_5F00_57_5F00_23.png

So it seems there must be a difference as the author of this method (all hail Microsoft) used both.

Thanks for reading

*This post is locked for comments

I have the same question (0)

All responses (6)

Answers (1)

Suggested answer

István Orosz 2,137 on at

Like (0)

Report

Hi,

The selectForUpdate() sets a property on the tablebuffer, when the select is performed next time the record is locked. When select forUpdate selects records for update only.

Pleas see this article: Difference between forUpdate keyword and selectForUpdate.

Kind regards,

István

Was this reply helpful? Yes No
Pete Alberts 3,542 on at

Like (0)

Report

Thank you very much

So in summary:

selectForUpdate: selects for update AND locks record

forupdate: only selects for update

Correct?

This still does not explain why the find method in CompanyImage uses both.

(I read the article you referenced before I posted this.)

This also brings me to a related question: Why is the source code for these methods not available? It would make my life much easier if I could just "Go To Definition".

Was this reply helpful? Yes No
Suggested answer

Mea_ 60,284 on at

Like (0)

Report

Hi Pete Alberts,

selectForUpdate and forupdate work identically. The main difference between two - is the usage. You can pass a value to selectForUpdate() method to set it before actual select and you cannot put "if" statement or any condition to disable or enable "forupdate". So you use selectForUpdate() when you need to enable it base on a condition and "forupdate" when record is always selected for update.

Was this reply helpful? Yes No
Pete Alberts 3,542 on at

Like (0)

Report

Thanks man.

I got that. :)

Please look at the CompanyImage example I attached in the OP. As/if the two are (basically) identical, it means the Microsoft developer who wrote that find method didn't know what he was doing. Which is very unlikely, but seems to be the inevitable answer?

Was this reply helpful? Yes No
Verified answer

Mea_ 60,284 on at

Like (0)

Report

Looking at index hint in the select statement (that is deprecated since 2012) I would say its very old legacy code that may be created before MS. Also please remember that standard code has tons of BP violations, so it's not always ideal. It works but does select for update 2 times that is not a big deal.

Was this reply helpful? Yes No
István Orosz 2,137 on at

Like (0)

Report

ievgen is right, the logic is the same in AX2009 also:

Was this reply helpful? Yes No