STRING versus CHAR/VARCHAR
Genero BDL supports the STRING
data
type in addition to CHAR
and VARCHAR
. While the
STRING
data type is useful in certain situations, there are times when you should
use CHAR
or VARCHAR
instead.
Genero Business Development Language (BDL) introduces a new data type named
STRING
, which is similar to VARCHAR
but without a size limit. The
STRING
data type does not exist in IBM®
Informix® 4GL. The STRING
data type
implementation is optimized for memory usage; unlike CHAR
/VARCHAR
,
BDL will only allocate the memory needed to hold the actual character string value in a
STRING
variable.
A STRING
variable is typically used within utility functions (for example, to
hold the path to a file). Another typical usage is with CONSTRUCT
, to hold the SQL
condition. The STRING
variable can then be completed to build the SQL text and
passed to the PREPARE
or DECLARE
instruction.
STRING
variables can be used in SQL statements. However, it is recommended to
use the CHAR
/VARCHAR
variables that match the size of the
corresponding CHAR
/VARCHAR
database columns.
The STRING
data type has a number of built-in methods that are very useful and
will reduce source code, such as getLength()
.