For storing strings of letters, numbers and symbols.
CHAR [ ( max-length ) ]
CHARACTER [ ( max-length ) ]
CHARACTER VARYING [ ( max-length ) ]
VARCHAR [ ( max-length ) ]
UNIQUEIDENTIFIERSTR
CHAR Character data of maximum length max-length bytes. If max-length is omitted, the default is 1. The maximum size allowed is 32KB – 1. See Notes for restrictions on CHAR data greater than 255 bytes.
See the notes below on character data representation in the database, and on storage of long strings.
All CHAR values are blank padded up to max-length, regardless of whether the BLANK PADDING option is specified. When multibyte character strings are held as a CHAR type, the maximum length is still in bytes, not characters.
CHARACTER VARYING Same as VARCHAR.
LONG VARCHAR Arbitrary length character data. The maximum size is limited by the maximum size of the database file (currently 2 gigabytes).
TEXT This is a user-defined data type. It is implemented as a LONG VARCHAR allowing NULL.
VARCHAR Same as CHAR, except that no blank padding is added to the storage of these strings, and VARCHAR strings can have a maximum length of (32KB – 1). See Notes for restrictions on VARCHAR data greater than 255 bytes.
UNIQUEIDENTIFIERSTR Domain implemented as CHAR( 36 ). This data type is used for remote data access, when mapping Microsoft SQL Server uniqueidentifier columns.
As a separately licensed option, Sybase IQ supports Character Large Object (CLOB) data with a length ranging from zero (0) to 512TB (terabytes) for an IQ page size of 128KB or 2PB (petabytes) for an IQ page size of 512KB. (The maximum length is equal to 4GB multiplied by the database page size.) For more information, see Large Objects Management in Sybase IQ.
Table 4-1 lists the storage size of character data.
Data type |
Column definition |
Input data |
Storage |
|---|---|---|---|
CHARACTER, CHAR |
width of (32K – 1) bytes |
(32K – 1) bytes |
(32K – 1) bytes |
VARCHAR, CHARACTER VARYING |
width of (32K – 1) bytes |
(32K – 1) bytes |
(32K – 1) bytes |
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 character set used by your system. You can find documentation about character sets in the documentation for your operating system.
On Windows, 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 different machine using a different code page, those special characters are retrieved from the database using the original code page representation. With the new code page, they appear on the screen to be the wrong characters.
This problem also appears if you have two clients using the same multiuser server, but running with different code pages. Data inserted or updated by one client might appear incorrect to another.
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 do 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.
All index types, except DATE, TIME, and DTTM, are supported for CHAR data and VARCHAR data less than or equal to 255 bytes in length.
Only the default index, WD, and CMP index types are supported for CHAR and VARCHAR columns over 255 bytes. You cannot create an LF, HG, HNG, DATE, TIME, or DTTM index for these columns.
The CHARACTER (n) alternative for CHAR is not supported in Adaptive Server Enterprise.
Sybase IQ does not support the NCHAR, NVARCHAR, UNICHAR, and UNIVARCHAR data types provided by Adaptive Server Enterprise. Sybase IQ supports Unicode in the CHAR and VARCHAR data types.
Sybase IQ supports a longer LONG VARCHAR data type than Adaptive Server Anywhere. For more information on the Sybase IQ data type LONG VARCHAR, see Large Objects Management in Sybase IQ.
For compatibility between Sybase IQ and Adaptive Server Enterprise, always specify a length for character data types.
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 are stored separate from the row containing the long string value.
There are several functions (see SQL Functions) 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.
