Client application code-set conversion

These topics summarize the code-set conversion that a client product performs.

For more general information about code-set conversion, see Perform code-set conversion.

The client application automatically performs code-set conversion between the client and database code sets when both of these conditions are true:
  • The code sets of the client and database locales do not match.
  • A valid object code-set conversion exists for the conversion between the client and database code sets.

When the client application begins execution, it compares the names of the client and database locales to determine whether to perform code-set conversion. If CLIENT_LOCALE is not set, the client application assumes that the client locale is the default locale. If DB_LOCALE is not set, the client application assumes that the database locale is the same as the client locale (the value of the CLIENT_LOCALE setting).

If the client and database code sets are the same, no code-set conversion is needed. If the code sets do not match, however, the client application must determine whether the two code sets are convertible. Two code sets are convertible if the client can locate the associated code-set-conversion files. These code-set-conversion files must exist on the client computer.

On UNIX™, you can use the glfiles utility to obtain a list of code-set conversions that your Informix® product supports. For more information, see The glfiles utility (UNIX). On Windows™, you can examine the directory %INFORMIXDIR%\gls\cvY to determine the GLS code-set conversions that your Informix® product supports. For more information about this directory, see Code-set-conversion files.

If no code-set-conversion files exist, the client application generates a run time error when it starts to indicate incompatible code sets. If code-set-conversion files exist, the client application automatically performs code-set conversion when it sends data to or receives data from the database server.

When a client application performs code-set conversion, it assumes that:
  • All data values that are processes are handled in the client code set.
  • All databases that the client application accesses on a single database server use the same database locale, territory, and code set. When the client application opens a different database, it does not recheck the database locale to determine if the code set has changed.
Important: Check the eighth character field of the SQLWARN array for a warning flag after each request for a connection. If the two database locales do not match, the client application might be performing code-set conversion incorrectly. The client application continues to perform any code-set conversion based on the code set that DB_LOCALE supports. If you proceed with such a connection, it is your responsibility to understand the format of the data that is being exchanged.