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For Win32, they are plentiful and installed with many applications. At run time the application provides a connection string which defines the ODBC data source it wants to connect to and this in turn defines the ODBC driver which will handle this data source.
However, this is a rather simplistic description of what the driver manager does. The ODBC driver manager also:. It "hides" some of the differences between the drivers i. ODBC needs this to talk to drivers. ODBC directly with your driver.
You need both a driver manager and driver installed and tested before working with DBD:: The DSN is a way of referring to a particular driver and database by any name you wish. ODBC used to come bundled with a driver manager but this became inconvenient when the driver manager was updated. If you are running a packaged Linux like RedHat, Ubuntu, Fedora, Suse etc etc you'll usually find it packaged with unixODBC and using the package manager to install it is fairly straight forward.
However, make sure that if the driver manager is split into multiple packages you install the development package as well as that contains the C header files required by DBD:: If you cannot find an ODBC Driver Manager package for your OS you can download the source tar files for either of the driver managers above and build it yourself.
The problem is that DBI:: Multiple Active Statements MAS are concurrent statements created from the same database handle which both have pending actions on them e. You could get around this with caution by changing to a dynamic cursor. There is a "hack" in DBD:: For other drivers it depends. Think carefully before using multiple active statements. It is probably not portable and there is nearly always a better way of doing it.
If anyone wants to report success with a particular driver and multiple active statements I will collect them here. If you are using the Oracle or Microsoft ODBC drivers then you may get the following error when inserting dates into an Oracle database:. You can do this with:. This was originally a rt. As an aside, if anyone is reading this and can shed some light on the problem I'd love to hear from you.
The technical details are:. If you are creating temporary objects e. Your should read http: ODBC attribute to your prepare as follows:. If you are running a 32bit Perl on a 64bit Windows machine you will need to be aware there are two ODBC administrators and you need to create your DSNs with the right one.
You can find more about this than you'd probably care to know at http: This typically means that the web server itself does not have the same environment and permissions the web developer does. This situation, of course, can and does apply to Unix web servers.
Under Win32, however, the problems are usually slightly different. The system DSN is a "global" one, while the user is local to a user. Typically, as stated above, the web server is "logged in" as a different user than the web developer. This helps cause the situation where someone asks why a script succeeds from the command line, but fails when called from the web server. For file based drivers, rather than client server drivers, the file path is VERY important. There are a few things to keep in mind.
This applies to, for example, MS Access databases. This can be VERY important as services don't quite get the same access permissions to the mapped drive letters and , more importantly, the drive letters themselves are GLOBAL to the machine.
That means that if the service tries to access Z: I've tested this while I was developing a service -- it's ugly and worth avoiding at all costs. There is at least one way around that. The important value to change for the Access driver, for example, is the DBQ value. That's actually the file name of the Access database. The dbq parameter tells the access driver which file to use for the database. Please see "Why am I getting errors with bound parameters" below which collects all parameter issues together in one FAQ item.
If you are using a MS SQL Server driver and named parameters to procedures be very careful to use then in the same order they are defined in the procedure. The reason for this is that all SQL Server drivers we have seen describe procedures parameters in the order they are declared and ignore the order they are used in the SQL.
If you specify them out of order DBD:: ODBC will get details on p1 which are really for p2 etc. This can lead to data truncation errors and all sorts of other problems it is impossible for DBD:: ODBC to spot or workaround. Also see "Why do I get "Datetime field overflow" when attempting to insert a date into Oracle? ODBC's buffer and you will get the error above. This is most often seen with char N columns as the trailing spaces are returned by the driver so you are bound to overflow the buffer as soon as a non-ASCII characters is found.
You can attempt to trim the data to leave room for the encoding. Remove UTF-8 from your locale. This is the best solution as it is guaranteed to stop this error but if you have data which cannot be represented in 8 bit characters this won't help.
The following error can happen when using more than bind parameters in a single query with SQL Server It is known to fail for version The error message from the server can vary. Below is an example:. MS keep moving this around. If you want to build DBD:: You can get it as part of the Platform Development Kit, with some of the Visual Studio versions and occasionally from:.
The symptom is that sometimes when your statement handle goes out of scope and is hence destroyed your script pauses for a while. When your statement handle is destroyed with pending results the ODBC Driver needs to read all the results to clear the socket. In this way the statement destruction is speeded up since fewer rows you don't need are sent.
See DBI's cancel method and if you destroy a statement handle with pending results, call cancel before destruction. If you attempt to call a procedure using the do method and it outputs results e. Instead you should do the following:. You can get this error without using any Perl or DBD:: ODBC simply by doing:. Did you build DBD:: Some versions of Ubunutu Linux seem to install the libiodbc shared object without a libiodbc.
The key giveaway when you build DBD:: ODBC is a warning like this:. In the past this did not matter but a small bug in DBI introduced years ago causes attribute values to be fetched. You need to get a DBI release newer than 1. It is my fault. Basically, I changed DBD:: ODBC to use Devel:: Sorry, some things are as they are.
ODBC did not have this requirement. The simple answer is that MS Access only supports characters in a text column. Unfortunately some versions of the MS Access ODBC driver silently truncate the data instead of issuing a data truncation error so you are not aware of the truncation until you read it back. ADO the text column is really a memo column. I created this FAQ to try and bring them all together in one place and other FAQ entries point at this one as a number of them boil down to a single problem.
In some rare cases the default bind type might not be what you want. In all cases this overrides anything else that DBD:: This is usually the best method unless you prefer to use a cast in your SQL. The upshot of this is that DBD:: ODBC is sometimes lied to about parameters and will then bind your parameters incorrectly. This can lead to later errors when execute is called. This happens most commonly when using parameters in SQL with sub-selects.
Clearly in this example, the one and only parameter is for two. In Perl the most common reason for this is that you have bound column data in SQL which does not match the column type in the database and the ODBC driver cannot perform the necessary conversion.