Use Of Boolean Against Other Data Types

SQL Language StructureCommon Language Elements

Use of Boolean Against Other Data Types

Although BOOLEAN is not inherently convertible to any other data type, the strings 'true' and 'false' (case-insensitive) will be implicitly cast to BOOLEAN in value expressions.For example:

if (true > 'false') then ...

The value 'false' is converted to BOOLEAN.Any attempt to use the Boolean operators AND, NOT, OR and IS will fail.NOT 'False', for example, is invalid.

A BOOLEAN can be explicitly converted to and from string with CAST.UNKNOWN is not available for any form of casting.

Note	Other Notes The type is represented in the API with the `FB_BOOLEAN` type and `FB_TRUE` and `FB_FALSE` constants. The value `TRUE` is greater than the value `FALSE`.

Binary Data Types

Note	The types [fblangref50-datatypes-chartypes-binary] and [fblangref50-datatypes-chartypes-varbinary] are covered earlier in section [fblangref50-datatypes-chartypes].

BLOBs (Binary Large Objects) are complex structures used to store text and binary data of an undefined length, often very large.

Syntax

BLOB [SUB_TYPE <subtype>]
  [SEGMENT SIZE <segment size>]
  [CHARACTER SET <character set>]
  [COLLATE <collation name>]

If the SUB_TYPE and CHARACTER SET clauses are absent, then subtype BINARY (or 0) is used.If the SUB_TYPE clause is absent and the CHARACTER SET clause is present, then subtype TEXT (or 1) is used.

Shortened syntax

BLOB (<segment size>)
BLOB (<segment size>, <subtype>)
BLOB (, <subtype>)

Note	Formally, the `COLLATE` clause is not part of the data type declaration, and its position depends on the syntax of the statement.

Segment Size

Specifying the BLOB segment size is a throwback to times past, when applications for working with BLOB data were written in C (Embedded SQL) with the help of the gpre pre-compiler.Nowadays, it is effectively irrelevant.The segment size for BLOB data is determined by the client side and is usually larger than the data page size, in any case.