Sybase Adaptive Server Anywhere - Character Data Types

Character data types
264
Character data types
For storing strings of letters, numbers and symbols.
Adaptive Server Anywhere treats CHAR, VARCHAR, and LONG
VARCHAR columns all as the same type. Values up to 254 characters are
stored as short strings, with a preceding length byte. Any values that are
longer than 255 bytes are considered long strings. Characters after the 255th
byte are stored separate from the row containing the long string value.
There are several functions (see "SQL Functions" on page 303) that will
ignore the part of any string past the 255th character. They are soundex,
similar, and all of the date functions. Also, any arithmetic involving the
conversion of a long string to a number will work on only the first 255
characters. It would be extremely unusual to run in to one of these
limitations.
All other functions and all other operators work with the full length of long
strings.
Character data is placed in the database using the exact binary representation
that is passed from the application. This usually means that character data is
stored in the database with the binary representation of the current code
page. The code page is the character set representation used by IBM-
compatible personal computers. You can find documentation about code
pages in the documentation for your operating system.
Most code pages are the same for the first 128 characters. If you use special
characters from the top half of the code page (accented international
language characters), you must be careful with your databases. In particular,
if you copy the database to a machine that uses a different code page, those
special characters will be retrieved from the database using the original code
page representation. With the new code page, they will appear on the screen
to be the wrong characters.
This problem also appears if you have two clients using the same multi-user
server, but run with different code pages. Data inserted or updated by one
client may appear incorrect to the other.
This problem also shows up if a database is used across platforms.
PowerBuilder and many other Windows applications insert data into the
database in the standard ANSI character set. If non-Windows applications
attempt to use this data, they will not properly display or update the extended
characters.
This problem is quite complex. If any of your applications use the extended
characters in the upper half of the code page, make sure that all clients and
all machines using the database use the same or a compatible code page.
Function
Description
Character sets and
code pages