Double-byte character set considerations

These topics describe double-byte character set (DBCS) considerations as they apply to the database on the iSeries™ system.

A DBCS is a character set that represents each character with 2 bytes. The DBCS supports national languages that contain a large number of unique characters or symbols (the maximum number of characters that can be represented with 1 byte is 256 characters). Examples of such languages include Japanese, Korean, and Chinese.

• DBCS field data types
  There are two general kinds of double-byte character set (DBCS) data: bracketed-DBCS data and graphic (nonbracketed) DBCS data.
• DBCS field mapping considerations
  This topic shows what types of data mapping are valid between physical and logical files for double-byte character set (DBCS) fields
• DBCS field concatenation
  When fields are concatenated, the data types can change (the resulting data type is automatically determined by the system). You can follow these guidelines when double-byte character set (DBCS) fields are concatenated.
• DBCS field substring operations
  A substring operation allows you to use part of a field or constant in a logical file.
• Compare DBCS fields in a logical file
  When comparing two fields or a field and constants, fixed-length fields can be compared to variable-length fields as long as the types are compatible.
• Use DBCS fields in the Open Query File (OPNQRYF) command
  These topics discuss the use of double-byte character set (DBCS) fields for these Open Query File (OPNQRYF) command functions: wildcard, concatenation, and sort sequence functions. A table shows valid comparisons for DBCS fields through the OPNQRYF command.