dbDataReader

[Mr. X.]

Hello.
When I use in my program the dbDataReader,
I can open only one datareader, and if not, computer shouts an error that
there is already an opened datareader.

I have VS 2008.
Use mySql.
Windows 7.

Is that problem a specific problem for mysql?

How can I overcome that problem (open more then one datareader)?

Thanks

 

[Arne Vajhøj]

When I use in my program the dbDataReader,
I can open only one datareader, and if not, computer shouts an error
that there is already an opened datareader.

I have VS 2008.
Use mySql.
Windows 7.

Is that problem a specific problem for mysql?
No.

How can I overcome that problem (open more then one datareader)?

Use two connections !

Arne

 

[Mr. X.]

I get several sqls externally.
I need to run all the sqls in the same transaction,
so open other connection for each sql is not a good solution.

I don't know if datareader is the best.
Is there any other solution then using datareader (or can I use datareader
by some parameters that I can open more then one datareader).

Thanks

 

[Arne Vajhøj]

I get several sqls externally.
I need to run all the sqls in the same transaction,
so open other connection for each sql is not a good solution.

I don't know if datareader is the best.
Is there any other solution then using datareader (or can I use
datareader by some parameters that I can open more then one datareader).

For MS SQLServer you can specify:
MultipleActiveResultSets=true
in the connection string.

But not in MySQL. Or most other databases.

There you have two options:

1) read everything from the first query and close the
reader before you make the next query

2) use two connections and TransactionScope to put them
in a single transaction

Or maybe reconsider your logic. It is rather unusual to have
multiple queries that return many rows in a transaction.

Arne

 

[Mr. X.]

Well.
It seems I should be very careful when using several datasource.
I would like an example of TransactionScope use, please.

Thanks

 

[Arne Vajhøj]

It seems I should be very careful when using several datasource.

It is not that bad.

I would like an example of TransactionScope use, please.

MS has an example in the docs:

http://msdn.microsoft.com/en-us/library/system.transactions.transactionscope.aspx

Arne