Technical Reference Manual - InduSoft

Database Interface
To solve this problem, make sure you are using MySQL Connector/Net v6.2.0 and that the table you are
accessing exists in the database.
Q: Why is the Database Interface automatically closing some connections
A: By default, the Database Interface can have a maximum of 1000 connections. When this maximum is
exceeded, the oldest connection is automatically closed to allow the new connection and the Output window
displays an extended message describing which connection was closed and what was the last command
executed.
To increase the maximum number of database connections, open the project file (project_name.app) in a
text editor and change the following setting:
[StDB]
MaxConnections=number_of_connections
Keep in mind that increasing the maximum number of connections may decrease project performance.
Q: I configured my Connection String using the browser and the Data Link Properties Window. When I click
the Test button, it says "Test succeeded". However, when I run my project, the Database Interface displays
error messages, and I am not able to save data.
A: The Data Link Properties Window uses OLE DB to interface with the Database. IWS Database Interface
uses ADO.NET; therefore, you can have the OLE DB provider on your machine and be missing the ADO.NET
provider. It is also possible that you are using an ADO.NET provider that is not listed in the StADOSvr.ini
file. Please refer to Studio Database Gateway for more information about adding ADO.NET providers to the
StADOSvr.ini file.
Q: Why, when I update information in one line in the Grid object, is it updating more than one line in my
database
A: The grid object issues an update command in the database using the values in all the columns for the
specific row that you are trying to update. If you have rows with duplicate values, you might see this problem.
If your table has a primary key or any other unique field that you do not want to display in the Grid object,
you can add it to the Columns but specify the Width 0. This will fix the problem.
Q: Why do I have to use a separate Column to store the milliseconds on my database
A: Some databases do not support milliseconds in the Time Stamp field. IWS Database interface, by default,
requires another column for the milliseconds. If your database can handle milliseconds, or if you do not want
to record the milliseconds, you can change the default behavior in the Advanced settings. Note that some
databases are able to store milliseconds, but they have lower precision. If you mix different databases with
different precisions in redundant mode, you can get synchronization problems.
Q: My project works fine when I run in emulation mode. But when I send to the Windows Embedded device, it
cannot communicate with my database.
A: It might be the case that your Windows Embedded device does not have the .Net Framework or that it does
not have the provider that you are using. Try to use the gateway remotely by following the instructions in
Linking the Database Through a Remote DB Provider.
Q: When I try to connect to the database, why do I receive the message, Error to create connection
class
A: The .Net Provider that you are trying to use is not installed on your machine. This error message is usually
followed by the provider name; if you are using the Sybase database, for instance, the message is followed
by [iAnywhere.Data.AsaClient.AsaConnection]. The Provider is the iAnywhere.Data.AsaClient. You can
check if the provider is installed on your machine by going to the Control Panel > Administrative Tools > Microsoft .Net
Framework x.x Configuration. The provider should be listed in the Assembly Cache.
Q: What if I have the provider assembly (usually a .dll file) but it is not listed in the AssemblyCache
A: If your assembly has a strong name, you can register it in the Assembly Cache using the gcautil
program. Or it should work if you copy your assembly to the same folder as the StADOSvr.exe (usually the
[…]\InduSoft Web Studio v7.1\Bin folder).
Q: I am not able to access my table from the Grid when I use a specific condition. But if no condition is
applied, it works fine. Why is that
A: You should check for the following items:
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