PROCEDURE

CREATE PROCEDURE

Available in: DSQL, ESQL

Description: Creates a stored procedure.

Syntax:

CREATE PROCEDURE procname
   [(<inparam> [, <inparam> ...])]
   [RETURNS (<outparam> [, <outparam> ...])]
AS
   [<declarations>]
BEGIN
   [<PSQL statements>]
END

<inparam>       ::=  <param_decl> [{= | DEFAULT} value]
<outparam>      ::=  <param_decl>
<param_decl>    ::=  paramname <type> [NOT NULL] [COLLATE collation]
<type>          ::=  sql_datatype | [TYPE OF] domain
<declarations>  ::=  See PSQL::DECLARE for the exact syntax

/* If sql_datatype is a string type, it may include a character set */

Domains supported in parameter and variable declarations

Changed in: 2.1

Description: Firebird 2.1 and up support the use of domains instead of SQL datatypes when declaring input/output parameters and local variables. With the “TYPE OF” modifier only the domain's type is used, not its NOT NULL setting, CHECK constraint and/or default value.

Example:

create domain bool3
  smallint
  check (value is null or value in (0,1));

create domain bigposnum
  bigint
  check (value >= 0);

/* Determines if A is a multiple of B: */
set term #;
create procedure ismultiple (a bigposnum, b bigposnum)
  returns (res bool3)
as
  declare ratio type of bigposnum;      -- ratio is a bigint
  declare remainder type of bigposnum;  -- so is remainder
begin
  if (a is null or b is null) then res = null;
  else if (b = 0) then
  begin
    if (a = 0) then res = 1; else res = 0;
  end
  else
  begin
    ratio = a / b;                      -- integer division!
    remainder = a - b*ratio;
    if (remainder = 0) then res = 1; else res = 0;
  end
end#
set term ;#

Warning

If you change a domain's definition, existing PSQL code using that domain may become invalid. If this happens, the system table field RDB$VALID_BLR will be set to 0 for any procedure or trigger whose code is no longer valid. If you have changed a domain, the following query will find the code modules that depend on it and report the state of RDB$VALID_BLR:

select * from (
  select 'Procedure', rdb$procedure_name, rdb$valid_blr from rdb$procedures
    union
  select 'Trigger', rdb$trigger_name, rdb$valid_blr from rdb$triggers
) (type, name, valid)
where exists
  (select * from rdb$dependencies
   where rdb$dependent_name = name and rdb$depended_on_name = 'MYDOMAIN')

/* Replace MYDOMAIN with the actual domain name. Use all-caps if the domain
   was created case-insensitively. Otherwise, use the exact capitalisation. */

Unfortunately, not all PSQL invalidations will be reflected in the RDB$VALID_BLR field. It is therefore advisable to look at all the procedures and triggers reported by the above query, even those having a 1 in the “VALID” column.

Please notice that for PSQL modules inherited from earlier Firebird versions (including a number of system triggers, even if the database was created under Firebird 2.1 or higher), RDB$VALID_BLR is NULL. This does not indicate that their BLR is invalid.

The isql commands SHOW PROCEDURES and SHOW TRIGGERS flag modules whose RDB$VALID_BLR field is zero with an asterisk. SHOW PROCEDURE PROCNAME and SHOW TRIGGER TRIGNAME, which display individual PSQL modules, do not signal invalid BLR.

COLLATE in variable and parameter declarations

Changed in: 2.1

Description: Firebird 2.1 and up allow COLLATE clauses in declarations of input/output parameters and local variables.

Example:

create procedure SpanishToDutch
  (es_1 varchar(20) character set iso8859_1 collate es_es,
   es_2 my_char_domain collate es_es)
returns
  (nl_1 varchar(20) character set iso8859_1 collate du_nl,
   nl_2 my_char_domain collate du_nl)
as
declare s_temp varchar(100) character set utf8 collate unicode;
begin
  ...
  ...
end

NOT NULL in variable and parameter declarations

Changed in: 2.1

Description: Firebird 2.1 and up allow NOT NULL constraints in declarations of input/output parameters and local variables.

Example:

create procedure RegisterOrder(order_no int not null, description varchar(200) not null)
returns
  (ticket_no int not null)
as
declare temp int not null;
begin
  ...
  ...
end

Default argument values

Changed in: 2.0

Description: It is now possible to provide default values for stored procedure arguments, allowing the caller to omit one or more items (possibly even all) from the end of the argument list.

Syntax:

CREATE PROCEDURE procname (<inparam> [, <inparam> ...])
   ...

<inparam>  ::=  paramname datatype [{= | DEFAULT} value]
Important: If you provide a default value for a parameter, you must do the same for any and all parameters following it.

BEGIN ... END blocks may be empty

Changed in: 1.5

Description: BEGIN ... END blocks may be empty in Firebird 1.5 and up, allowing you to write stub code without having to resort to dummy statements.

Example:

create procedure grab_ints (a integer, b integer)
as
begin
end

ALTER PROCEDURE

Available in: DSQL, ESQL

Default argument values

Added in: 2.0

Description: You can now provide default values for stored procedure arguments, allowing the caller to omit one or more items from the end of the argument list. See CREATE PROCEDURE for syntax and details.

Example:

alter procedure TestProc
  (a int, b int default 1007, s varchar(12) = '-')
  ...

COLLATE in variable and parameter declarations

Changed in: 2.1

Description: Firebird 2.1 and up allow COLLATE clauses in declarations of input/output parameters and local variables. See CREATE PROCEDURE for syntax and details.

Domains supported in parameter and variable declarations

Changed in: 2.1

Description: Firebird 2.1 and up support the use of domains instead of SQL datatypes when declaring input/output parameters and local variables. See CREATE PROCEDURE for syntax and details.

NOT NULL in variable and parameter declarations

Changed in: 2.1

Description: Firebird 2.1 and up allow NOT NULL constraints in declarations of input/output parameters and local variables. See CREATE PROCEDURE for syntax and details.

Restriction on altering used procedures

Changed in: 2.0, 2.0.1

Description: In Firebird 2.0 only, a restriction is in place which prevents anyone from dropping, altering or recreating a trigger or stored procedure if it has been used since the database was opened. This restriction has been removed again in version 2.0.1. Still, performing these operations on a live database is potentially risky and should only be done with the utmost care.

CREATE OR ALTER PROCEDURE

Available in: DSQL

Added in: 1.5

Description: If the procedure does not yet exist, it is created just as if CREATE PROCEDURE were used. If it already exists, it is altered and recompiled. Existing permissions and dependencies are preserved.

Syntax: Exactly the same as for CREATE PROCEDURE.

DROP PROCEDURE

Available in: DSQL, ESQL

Restriction on dropping used procedures

Changed in: 2.0, 2.0.1

Description: In Firebird 2.0 only, a restriction is in place which prevents anyone from dropping, altering or recreating a trigger or stored procedure if it has been used since the database was opened. This restriction has been removed again in version 2.0.1. Still, performing these operations on a live database is potentially risky and should only be done with the utmost care.

RECREATE PROCEDURE

Available in: DSQL

Added in: 1.0

Description: Creates or recreates a stored procedure. If a procedure with the same name already exists, RECREATE PROCEDURE will try to drop it and create a new procedure. RECREATE PROCEDURE will fail if the existing SP is in use.

Syntax: Exactly the same as CREATE PROCEDURE.

Restriction on recreating used procedures

Changed in: 2.0, 2.0.1

Description: In Firebird 2.0 only, a restriction is in place which prevents anyone from dropping, altering or recreating a trigger or stored procedure if it has been used since the database was opened. This restriction has been removed again in version 2.0.1. Still, performing these operations on a live database is potentially risky and should only be done with the utmost care.