SQL Toolkit

[pinguu]

Hello,

Just have a quick question about the SQL toolkit (v2.3).

Is there a way to lock an ms sql database upon connection?

I'm currently doing the following sequence:

DBConnect()

DBSetDatabase()

DBActivateSQL()

DBFree()

DBDisconnect()

However, when I do a connect, I don't want to have a same application to be able to read the database.

My understanding is that if I create 2 separate executable with the same functions both .exe will be able to access the ms sql database at the same time.

I tried to implement an optimistic concurrency but I don't think it's working.

[Jattie]

Off the top of my head, I don't think you can, i.e. I do not think that the feature is implemented in the toolkit since the toolkit aims to provide a generic interface to CVI for database connectivity.

I am curious however, why you want to do this. The very reason for using a database is to get access to the same dataset from multiple connections. Maybe you should use a file instead of a database of you want locked access. 

[pinguu]

Thanks for the reply; however, it was done in a local file for locking.

It's just a requirement that I need to do.

I'm trying to use DBBeginTran() and DBCommit(); but still trying it out.

For example, multiple users must be able to obtain, let's say a counter, from the SQL db; however, users must not have a duplicate of the counter.

Steps:

1. user1 gets counter from DB (counter = 1)

2. user1 increments counter++

3. user2 connects and gets counter from DB (counter = 1)

4. user1 updates counter in DB to counter = 2

5. user2 increments counter++

6. user2 updates counter in DB but realize counter read (step3) does not match...

I want to avoid this situation because user1 and user2 will have a counter of 1, where it's supposed to be user1 have counter = 1 and user2 have counter = 2, etc.