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 TRIGGERFUNCTION 

External UDR Procedures

A stored procedure can also be located in an external module.In this case, instead of a procedure body, the CREATE PROCEDURE specifies the location of the procedure in the external module using the EXTERNAL clause.The optional NAME clause specifies the name of the external module, the name of the procedure inside the module, and — optionally — user-defined information.The required ENGINE clause specifies the name of the UDR engine that handles communication between Firebird and the external module.The optional AS clause accepts a string literal “body”, which can be used by the engine or module for various purposes.

Who Can Create a Procedure

The CREATE PROCEDURE statement can be executed by:

The user executing the CREATE PROCEDURE statement becomes the owner of the table.

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Examples

  1. Creating a stored procedure that inserts a record into the BREED table and returns the code of the inserted record:

    CREATE PROCEDURE ADD_BREED (
  NAME D_BREEDNAME, /* Domain attributes are inherited */
  NAME_EN TYPE OF D_BREEDNAME, /* Only the domain type is inherited */
  SHORTNAME TYPE OF COLUMN BREED.SHORTNAME,
    /* The table column type is inherited */
  REMARK VARCHAR(120) CHARACTER SET WIN1251 COLLATE PXW_CYRL,
  CODE_ANIMAL INT NOT NULL DEFAULT 1
)
RETURNS (
  CODE_BREED INT
)
AS
BEGIN
  INSERT INTO BREED (
    CODE_ANIMAL, NAME, NAME_EN, SHORTNAME, REMARK)
  VALUES (
    :CODE_ANIMAL, :NAME, :NAME_EN, :SHORTNAME, :REMARK)
  RETURNING CODE_BREED INTO CODE_BREED;
END

  2. Creating a selectable stored procedure that generates data for mailing labels (from employee.fdb):

    CREATE PROCEDURE mail_label (cust_no INTEGER)
RETURNS (line1 CHAR(40), line2 CHAR(40), line3 CHAR(40),
         line4 CHAR(40), line5 CHAR(40), line6 CHAR(40))
AS
  DECLARE VARIABLE customer VARCHAR(25);
  DECLARE VARIABLE first_name VARCHAR(15);
  DECLARE VARIABLE last_name VARCHAR(20);
  DECLARE VARIABLE addr1 VARCHAR(30);
  DECLARE VARIABLE addr2 VARCHAR(30);
  DECLARE VARIABLE city VARCHAR(25);
  DECLARE VARIABLE state VARCHAR(15);
  DECLARE VARIABLE country VARCHAR(15);
  DECLARE VARIABLE postcode VARCHAR(12);
  DECLARE VARIABLE cnt INTEGER;
BEGIN
  line1 = '';
  line2 = '';
  line3 = '';
  line4 = '';
  line5 = '';
  line6 = '';

  SELECT customer, contact_first, contact_last, address_line1,
    address_line2, city, state_province, country, postal_code
  FROM CUSTOMER
  WHERE cust_no = :cust_no
  INTO :customer, :first_name, :last_name, :addr1, :addr2,
    :city, :state, :country, :postcode;

  IF (customer IS NOT NULL) THEN
    line1 = customer;
  IF (first_name IS NOT NULL) THEN
    line2 = first_name || ' ' || last_name;
  ELSE
    line2 = last_name;
  IF (addr1 IS NOT NULL) THEN
    line3 = addr1;
  IF (addr2 IS NOT NULL) THEN
    line4 = addr2;

  IF (country = 'USA') THEN
  BEGIN
    IF (city IS NOT NULL) THEN
  	  line5 = city || ', ' || state || '  ' || postcode;
  	ELSE
      line5 = state || '  ' || postcode;
  END
  ELSE
  BEGIN
    IF (city IS NOT NULL) THEN
  	  line5 = city || ', ' || state;
  	ELSE
      line5 = state;
    line6 = country || '    ' || postcode;
  END

  SUSPEND; -- the statement that sends an output row to the buffer
           -- and makes the procedure "selectable"
END

  3. With DEFINER set for procedure p, user US needs only the EXECUTE privilege on p.If it were set for INVOKER, either the user or the procedure would also need the INSERT privilege on table t.

    set term ^;
create procedure p (i integer) SQL SECURITY DEFINER
as
begin
  insert into t values (:i);
end^
set term ;^

grant execute on procedure p to user us;
commit;

connect 'localhost:/tmp/17.fdb' user us password 'pas';
execute procedure p(1);
See also

[fblangref50-ddl-proc-crtoralter], [fblangref50-ddl-proc-alter], [fblangref50-ddl-proc-recreate], [fblangref50-ddl-proc-drop]

ALTER PROCEDURE

Alters a stored procedure

Available in

DSQL, ESQL

Syntax
ALTER PROCEDURE procname [ ( [ <in_params> ] ) ]
  [RETURNS (<out_params>)]
  {<psql_procedure> | <external-module-body>}

!! See syntax of CREATE PROCEDURE for further rules !!

The ALTER PROCEDURE statement allows the following changes to a stored procedure definition:

  • the set and characteristics of input and output parameters

  • local variables

  • code in the body of the stored procedure

After ALTER PROCEDURE executes, existing privileges remain intact and dependencies are not affected.

Altering a procedure without specifying the SQL SECURITY clause will remove the SQL Security property if currently set for this procedure.This means the behaviour will revert to the database default.

Caution

Take care about changing the number and type of input and output parameters in stored procedures.Existing application code and procedures and triggers that call it could become invalid because the new description of the parameters is incompatible with the old calling format.For information on how to troubleshoot such a situation, see the article The RDB$VALID_BLR Field in the Appendix.

Who Can Alter a Procedure

The ALTER PROCEDURE statement can be executed by:

  • Administrators

  • The owner of the stored procedure

  • Users with the ALTER ANY PROCEDURE privilege

ALTER PROCEDURE Example

Altering the GET_EMP_PROJ stored procedure.
ALTER PROCEDURE GET_EMP_PROJ (
  EMP_NO SMALLINT)
RETURNS (
  PROJ_ID VARCHAR(20))
AS
BEGIN
  FOR SELECT
      PROJ_ID
    FROM
      EMPLOYEE_PROJECT
    WHERE
      EMP_NO = :emp_no
    INTO :proj_id
  DO
    SUSPEND;
END
See also

[fblangref50-ddl-proc-create], [fblangref50-ddl-proc-crtoralter], [fblangref50-ddl-proc-recreate], [fblangref50-ddl-proc-drop]

CREATE OR ALTER PROCEDURE

Creates a stored procedure if it does not exist, or alters a stored procedure

Available in

DSQL

Syntax
CREATE OR ALTER PROCEDURE procname [ ( [ <in_params> ] ) ]
  [RETURNS (<out_params>)]
  {<psql_procedure> | <external-module-body>}

!! See syntax of CREATE PROCEDURE for further rules !!

The CREATE OR ALTER PROCEDURE statement creates a new stored procedure or alters an existing one.If the stored procedure does not exist, it will be created by invoking a CREATE PROCEDURE statement transparently.If the procedure already exists, it will be altered and compiled without affecting its existing privileges and dependencies.

CREATE OR ALTER PROCEDURE Example

Creating or altering the GET_EMP_PROJ procedure.
CREATE OR ALTER PROCEDURE GET_EMP_PROJ (
    EMP_NO SMALLINT)
RETURNS (
    PROJ_ID VARCHAR(20))
AS
BEGIN
  FOR SELECT
      PROJ_ID
    FROM
      EMPLOYEE_PROJECT
    WHERE
      EMP_NO = :emp_no
    INTO :proj_id
  DO
    SUSPEND;
END
See also

[fblangref50-ddl-proc-create], [fblangref50-ddl-proc-alter], [fblangref50-ddl-proc-recreate]

DROP PROCEDURE

Drops a stored procedure

Available in

DSQL, ESQL

Syntax
DROP PROCEDURE procname
Table 1. DROP PROCEDURE Statement Parameter
Parameter Description

procname

Name of an existing stored procedure

The DROP PROCEDURE statement deletes an existing stored procedure.If the stored procedure has any dependencies, the attempt to delete it will fail and raise an error.

Who Can Drop a Procedure

The DROP PROCEDURE statement can be executed by:

  • Administrators

  • The owner of the stored procedure

  • Users with the DROP ANY PROCEDURE privilege

DROP PROCEDURE Example

Deleting the GET_EMP_PROJ stored procedure.
DROP PROCEDURE GET_EMP_PROJ;
See also

[fblangref50-ddl-proc-create], [fblangref50-ddl-proc-recreate]

RECREATE PROCEDURE

Drops a stored procedure if it exists, and creates a stored procedure

Available in

DSQL

Syntax
RECREATE PROCEDURE procname [ ( [ <in_params> ] ) ]
  [RETURNS (<out_params>)]
  {<psql_procedure> | <external-module-body>}

!! See syntax of CREATE PROCEDURE for further rules !!

The RECREATE PROCEDURE statement creates a new stored procedure or recreates an existing one.If a procedure with this name already exists, the engine will try to drop it and create a new one.Recreating an existing procedure will fail at the COMMIT request if the procedure has dependencies.

Warning

Be aware that dependency errors are not detected until the COMMIT phase of this operation.

After a procedure is successfully recreated, privileges to execute the stored procedure, and the privileges of the stored procedure itself are dropped.

RECREATE PROCEDURE Example

Creating the new GET_EMP_PROJ stored procedure or recreating the existing GET_EMP_PROJ stored procedure.
RECREATE PROCEDURE GET_EMP_PROJ (
  EMP_NO SMALLINT)
RETURNS (
  PROJ_ID VARCHAR(20))
AS
BEGIN
  FOR SELECT
      PROJ_ID
    FROM
      EMPLOYEE_PROJECT
    WHERE
      EMP_NO = :emp_no
    INTO :proj_id
  DO
    SUSPEND;
END
See also

[fblangref50-ddl-proc-create], [fblangref50-ddl-proc-drop], [fblangref50-ddl-proc-crtoralter]