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Use of Column Type in Declarations

Input and output parameters or local variables can also be declared using the data type of columns in existing tables and views.The TYPE OF COLUMN clause is used for that, specifying relationname.columnname as its argument.

When TYPE OF COLUMN is used, the parameter or variable inherits only the data type and — for string types — the character set and collation.The constraints and default value of the column are ignored.

BLOB Data Types Syntax

The BLOB data types hold binary, character or custom format data of unspecified size.For more information, see [fblangref50-datatypes-bnrytypes].

BLOB Data Types Syntax
<blob_datatype> ::=
    BLOB [SUB_TYPE {subtype_num | subtype_name}]
    [SEGMENT SIZE seglen] [CHARACTER SET charset]
  | BLOB [(seglen [, subtype_num])]
  | BLOB [(, subtype_num)]
Table 1. Arguments for the Blob Data Types Syntax
Argument Description

charset

Character set (ignored for subtypes other than TEXT/1).

subtype_num

BLOB subtype number

subtype_name

BLOB subtype mnemonic name;this can be TEXT, BINARY, or one of the (other) standard or custom names defined in RDB$TYPES for RDB$FIELD_NAME = 'RDB$FIELD_SUB_TYPE'.

seglen

Segment size, cannot be greater than 65,535, defaults to 80 when not specified.See also [fblangref50-datatypes-seg-size]

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.