Double-byte character set considerations

 

A double-byte character set (DBCS) is a character set that represents each character with 2 bytes. The database on the i5/OS^® operating system supports DBCS.

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
  The table 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). Double-byte character set (DBCS) field concatenation follows these rules.

• DBCS field substring operations
  A substring operation allows you to use part of a field or constant in a logical file.

• Comparing DBCS fields in a logical file
  When you compare two fields or compare a field and constants, fixed-length fields can be compared to variable-length fields if the types are compatible. The table shows the valid comparisons for double-byte character set (DBCS) fields in a logical file.

• Using DBCS fields in the Open Query File (OPNQRYF) command
  Double-byte character set (DBCS) fields can be used for the wildcard, concatenation, and sort sequence functions of the Open Query File (OPNQRYF) command.

 

Parent topic:

Database programming