Character conversion guidelines

Data conversion might be required to map data between application and database code pages when your application and database do not use the same code page. Because mapping and data conversion require additional processing, application performance improves if the application and database use the same code page or the identity collating sequence.

Character conversion occurs in the following circumstances:
  • When a client or application runs in a code page that is different from the code page of the database that it accesses.

    The conversion occurs on the database server machine that receives the data. If the database server receives the data, character conversion is from the application code page to the database code page. If the application machine receives the data, conversion is from the database code page to the application code page.

  • When using Db2® Import, Export, or Load utilities, if the source code page for the data is different from the target code page.
Character conversion does not occur for the following objects:
  • File names.
  • Data targeted for or coming from a column for which the FOR BIT DATA attribute is assigned, or data that is used in an SQL operation whose result is FOR BIT, binary, or BLOB data.
  • A Db2 product or platform for which no supported conversion function to or from EUC or UCS-2 is installed.

The conversion function and conversion tables or DBCS conversion APIs that the database manager uses when it converts multibyte code pages depends on the operating system environment.

Note: Character string conversions between multibyte code pages, such as DBCS with EUC, might increase or decrease length of a string.

Extended UNIX Code (EUC) Code Page Support

Host variables that use graphic data in C or C++ applications require special considerations that include special precompiler, application performance, and application design issues.

Many characters in both the Japanese and Traditional Chinese EUC code pages require special methods of managing database and client application support for graphic data, which require double byte characters. Graphic data from these EUC code pages is stored and manipulated using the UCS-2 code set.