Changed in: 2.0
Description
Makes a blob filter known to the database.
Syntax''' _
DECLARE FILTER filtername INPUT_TYPE <sub_type> OUTPUT_TYPE <subtype> ENTRY_POINT 'function_name' MODULE_NAME 'library_name' <sub_type> ::= number | <mnemonic> <mnemonic> ::= binary | text | blr | acl | ranges | summary | format | transaction_description | external_file_description | user_defined
Example
declare filter Funnel input_type blr output_type text entry_point 'blr2asc' module_name 'myfilterlib'
User-defined mnemonics: If you want to define mnemonics for your own blob subtypes, you can add them to the RDB$TYPES system table as shown below. Once committed, the mnemonics can be used in subsequent filter declarations.
insert into rdb$types (rdb$field_name, rdb$type, rdb$type_name) values ('RDB$FIELD_SUB_TYPE', -33, 'MIDI')
The value for rdb$field_name must always be 'RDB$FIELD_SUB_TYPE'. If you define your mnemonics in all-uppercase, you can use them case-insensitively and unquoted in your filter declarations.