Firebird 2.0
PSQL Reference
Manual

(N)VARCHAR DATATYPES

Purpose

Use the VARCHAR and NCHAR VARYING datatypes to hold text values of a variable length.

Syntax

<varchar_type> ::=
     <varchar_keyword> ( <psql_integer> ) [ <char_set> ]
   | <nvarchar_keyword> ( <psql_integer> )

<varchar_keyword> ::=
   CHARACTER VARYING | VARCHAR

<nvarchar_keyword> ::=
     NCHAR VARYING
   | NATIONAL CHARACTER VARYING
   | NATIONAL CHAR VARYING

<char_set> ::=
   CHARACTER SET <identifier>


Semantics

The VARCHAR(n) datatype contains text of varying length, up to a maximum of n characters. The maximum size is 32,767 bytes, which can be 10,992 to 32,767 characters, depending on the character size (1..3 bytes). You must supply n; there is no default to 1.

Firebird converts from variable-length character data to fixed-length character data by adding spaces to the value in the varying column until the column reaches its maximum length n. In the reverse conversion, trailing blanks are removed from the text.

The main advantage of using the VARCHAR(n) datatype are that it saves memory space during the execution of PSQL programs.

Examples

The below examples define a type to hold 32 characters in Unicode and a type to hold 128 characters in the ISO8859_1 character set (a.k.a. “latin1”):

VARCHAR(32) CHARACTER SET UNICODE_FSS
NCHAR VARYING (128)


See also

Character sets and collation orders in the SQL Reference Manual


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