This CREATE FUNCTION (SQL table) statement creates an SQL table function
at the current server. The function returns a single result table.
You can embed this statement in an application program, or you can issue
this statement interactively. It is an executable statement that can be dynamically
prepared.
The privileges held by the authorization ID of the statement must include
at least one of the following:
The privileges held by the authorization id of the statement must include
at least one of the following:
- For the SYSFUNCS catalog view and SYSPARMS catalog table:
- The INSERT privilege on the table, and
- The system authority *EXECUTE on library QSYS2
- Administrative Authority
The privileges held by the authorization ID of the statement must also
include at least one of the following:
- The following system authorities:
- *USE to the Create Service Program (CRTSRVPGM) command or
- Administrative authority
If a distinct type is referenced, the privileges held by the authorization ID of
the statement must include at least one of the following:
- For each distinct type identified in the statement:
- The USAGE privilege on the distinct type, and
- The system authority *EXECUTE on the library containing the distinct type
- Administrative authority
For information on the system authorities corresponding to SQL privileges,
see Corresponding System Authorities When Checking Privileges to a Table or View and Corresponding System Authorities When Checking Privileges to a Distinct Type.
>>-CREATE FUNCTION--function-name------------------------------->
>--(--+---------------------------+--)-------------------------->
| .-,---------------------. |
| V | |
'---parameter-declaration-+-'
.-,-----------------------.
V |
>--RETURNS TABLE--(----column-name--data-type2-+--)------------->
>--LANGUAGE SQL--option-list--+----------------------+--SQL-routine-body-><
'-SET OPTION-statement-'
parameter-declaration:
|--parameter-name--data-type1-----------------------------------|
data-type1, data-type2:
|--+-built-in-type------+---------------------------------------|
'-distinct-type-name-'
built-in-type:
|--+-+---SMALLINT---+--------------------------------------------------------------------------+--|
| +-+-INTEGER-+--+ |
| | '-INT-----' | |
| '---BIGINT-----' |
| .-(5,0)------------------------. |
+-+-+-DECIMAL-+-+--+------------------------------+-----------------------------------------+
| | '-DEC-----' | | .-,0--------. | |
| '-NUMERIC-----' '-(--integer--+-----------+--)-' |
| '-, integer-' |
| .-(--53--)------. |
+-+-FLOAT--+---------------+-+--------------------------------------------------------------+
| | '-(--integer--)-' | |
| +-REAL---------------------+ |
| | .-PRECISION-. | |
| '-DOUBLE--+-----------+----' |
| .-(--1--)-------. |
+-+-+-+-CHARACTER-+--+---------------+----------+--+----------------+---------------------+-+
| | | '-CHAR------' '-(--integer--)-' | +-FOR BIT DATA---+ | |
| | '-+-+-CHARACTER-+--VARYING-+--(--integer--)-' +-FOR SBCS DATA--+ | |
| | | '-CHAR------' | +-FOR MIXED DATA-+ | |
| | '-VARCHAR----------------' '-ccsid-clause---' | |
| | .-(--1M--)-------------. | |
| '-----+-+-CHARACTER-+--LARGE OBJECT-+------+----------------------+--+----------------+-' |
| | '-CHAR------' | '-(--integer--+---+--)-' +-FOR SBCS DATA--+ |
| '-CLOB------------------------' +-K-+ +-FOR MIXED DATA-+ |
| +-M-+ '-ccsid-clause---' |
| '-G-' |
| .-(--1--)-------. |
+-+---GRAPHIC----+---------------+-------+--+--------------+--------------------------------+
| | '-(--integer--)-' | '-ccsid-clause-' |
| +-+-GRAPHIC VARYING-+--(--integer--)---+ |
| | '-VARGRAPHIC------' | |
| | .-(--1M--)-------------. | |
| '---DBCLOB----+----------------------+-' |
| '-(--integer--+---+--)-' |
| +-K-+ |
| +-M-+ |
| '-G-' |
| .-(--1--)-------. |
+-+-+-BINARY--+---------------+---------+-----------------+---------------------------------+
| | | '-(--integer--)-' | | |
| | '-+-BINARY VARYING-+--(--integer--)-' | |
| | '-VARBINARY------' | |
| | .-(--1M--)-------------. | |
| '---+-BLOB----------------+----+----------------------+-' |
| '-BINARY LARGE OBJECT-' '-(--integer--+---+--)-' |
| +-K-+ |
| +-M-+ |
| '-G-' |
+-+-DATE-------------------+----------------------------------------------------------------+
| | .-(--0--)-. | |
| +-TIME--+---------+------+ |
| | .-(--6--)-. | |
| '-TIMESTAMP--+---------+-' |
| .-(--200--)-----. |
+---DATALINK--+---------------+--+--------------+-------------------------------------------+
| '-(--integer--)-' '-ccsid-clause-' |
'---ROWID-----------------------------------------------------------------------------------'
ccsid-clause:
.-NOT NORMALIZED-.
|--CCSID--integer--+----------------+---------------------------|
'-NORMALIZED-----'
option-list:
(1) .-NOT DETERMINISTIC-.
|--+-------------------------+-------+-------------------+------>
'-SPECIFIC--specific-name-' '-DETERMINISTIC-----'
.-EXTERNAL ACTION----. .-READS SQL DATA----.
>--+--------------------+--+-------------------+---------------->
'-NO EXTERNAL ACTION-' +-CONTAINS SQL------+
'-MODIFIES SQL DATA-'
.-STATIC DISPATCH-. .-CALLED ON NULL INPUT-------.
>--+-----------------+--+----------------------------+---------->
'-RETURNS NULL ON NULL INPUT-'
.-FENCED-----.
>--+------------+----DISALLOW PARALLEL-------------------------->
'-NOT FENCED-'
>--+----------------------+-------------------------------------|
'-CARDINALITY--integer-'
Notes:
- The optional clauses can be specified in a different
order.
SQL-routine-body:
|----SQL-control-statement--------------------------------------|
- function-name
- Names the user-defined function. The combination of name, schema name,
the number of parameters, and the data type of each parameter (without regard
for any length, precision, scale, or CCSID attributes of the data type) must
not identify a user-defined function that exists at the current server.
For SQL naming, the function will be created in the schema specified by the
implicit or explicit qualifier.
For system naming, the function will
be created in the schema that is specified by the qualifier. If no qualifier
is specified:
- If the value of the CURRENT SCHEMA special register is *LIBL, the function
will be created in the current library (*CURLIB).
- Otherwise, the function will be created in the current schema.
In general, more than one function can have the same name if the
function signature of each function is unique.
Certain function names
are reserved for system use. For more information see Choosing the Schema and Function Name.
- (parameter-declaration,...)
- Specifies the number of parameters of the function and the data type
of each parameter. Although not required, you can give each parameter a name.
The maximum number of parameters allowed is 90.
- parameter-name
- Names the parameter. The name is used to refer to the parameter
within the body of the function. The name cannot be the same as any other parameter-name in the parameter list.
- data-type1
- Specifies the data type of the input parameter. The data
type can be a built-in data type or a distinct data type.
- built-in-type
- Specifies a built-in data type. For a more complete description of each
built-in data type, see CREATE TABLE.
- distinct-type-name
- Specifies a distinct type. The length, precision, or scale attributes
for the parameter are those of the source type of the distinct type (those
specified on CREATE DISTINCT TYPE). For more information on creating a distinct
type, see CREATE DISTINCT TYPE.
If the name of the distinct type is unqualified,
the database manager resolves the schema name by searching the schemas in
the SQL path.
If a CCSID is specified, the parameter will be converted to that
CCSID prior to passing it to the function. If a CCSID is not specified, the
CCSID is determined by the default CCSID at the current server at the time
the function is invoked.
- RETURNS TABLE
- Specifies the output table of the function.
Assume the number of parameters
is N. There must be no more than (247-(N*2))/2 columns.
- column-name
- Specifies the name of a column of the output table. Do not specify the
same name more than once.
- data-type2
- Specifies the data type and attributes of the output.
You can specify any built-in data type (except LONG VARCHAR, or LONG VARGRAPHIC)
or a distinct type.
If a CCSID is specified and the CCSID of the return
data is encoded in a different CCSID, the data is converted to the specified
CCSID.
If a CCSID is not specified the return data is converted to the
CCSID of the job (or associated graphic CCSID of the job for graphic string
return values), if the CCSID of the return data is encoded in a different
CCSID. To avoid any potential loss of characters during the conversion, consider
explicitly specifying a CCSID that can represent any characters that will
be returned from the function. This is especially important if the data type
is graphic string data. In this case, consider using CCSID 1200 or 13488 (UTF-16
or UCS-2 graphic string data).
- LANGUAGE SQL
- Specifies that this is an SQL function.
- SPECIFIC specific-name
- Provides a unique name for the function. The name is implicitly or explicitly
qualified with a schema name. The name, including the schema name, must not
identify the specific name of another function or procedure that exists at
the current server. If unqualified, the implicit qualifier is the same as
the qualifier of the function name. If qualified, the qualifier must be the
same as the qualifier of the function name.
If specific name is not specified,
it is set to the function name. If a function or procedure with that specific
name already exists, a unique name is generated similar to the rules used
to generate unique table names.
- DETERMINISTIC or NOT DETERMINISTIC
- Specifies whether the function is deterministic.
- NOT DETERMINISTIC
- Specifies that the function will not always return the same result from
successive function invocations with identical input arguments. NOT DETERMINISTIC
should be specified if the function contains a reference to a special register,
a non-deterministic function, or a sequence.
- DETERMINISTIC
- Specifies that the function will always return the same result from
successive invocations with identical input arguments.
- EXTERNAL ACTION or NO EXTERNAL ACTION
- Specifies whether the function contains an external action.
- EXTERNAL ACTION
- The function performs some external action (outside the scope of the
function program). Thus, the function must be invoked with each successive
function invocation. EXTERNAL ACTION should be specified if the function contains
a reference to another function that has an external action.
- NO EXTERNAL ACTION
- The function does not perform an external action. It need not be called
with each successive function invocation.
- CONTAINS SQL, READS SQL DATA, or MODIFIES
SQL DATA
- Specifies whether the function can execute any SQL statements and, if
so, what type. The database manager verifies that the SQL issued by the function is
consistent with this specification. See Appendix B. Characteristics of SQL statements for a detailed
list of the SQL statements that can be executed under each data access indication.
- CONTAINS SQL
- The function does not execute SQL statements that read or modify data.
- READS SQL DATA
- The function does not execute SQL statements that modify data.
- MODIFIES SQL DATA
- The function can execute any SQL statement except those statements that
are not supported in any function.
- STATIC DISPATCH
- Specifies that the function is dispatched statically. All functions
are statically dispatched.
- RETURNS NULL ON NULL INPUT or CALLED ON
NULL INPUT
- Specifies whether the function is called if any of the input arguments
is null at execution time.
- RETURNS NULL ON INPUT
- Specifies that the function is not invoked if any of the input arguments
is null. The result is the null value.
- CALLED ON NULL INPUT
- Specifies that the function is to be invoked, if any, or all, argument
values are null, making the function responsible for testing for null argument
values. The function can return a null or nonnull value.
- FENCED or NOT FENCED
- Specifies whether the SQL function runs in an environment that is isolated
from the database manager environment.
- FENCED
- The function will run in a separate thread.
FENCED functions cannot
keep SQL cursors open across individual calls to the function. However, the
cursors in one thread are independent of the cursors in any other threads
which reduces the possibility of cursor name conflicts.
- NOT FENCED
- The function may run in the same thread as the invoking SQL statement.
NOT FENCED functions can keep SQL cursors open across individual calls to
the function. Since cursors can be kept open, the cursor position will also
be preserved between calls to the function. However, cursor names may conflict
since the UDF is now running in the same thread as the invoking SQL statement
and other NOT FENCED UDFs.
NOT FENCED functions usually perform better
than FENCED functions.
- DISALLOW PARALLEL
- Specifies that the function cannot be run in parallel. Table functions
cannot run in parallel.
- CARDINALITY integer
- This optional clause provides an estimate of the expected number of
rows to be returned by the function for optimization purposes. Valid values
for integer range from 0 to 2 147 483 647 inclusive.
If the CARDINALITY
clause is not specified for a table function, the database manager will assume a finite
value as a default.
- SET OPTION-statement
- Specifies the options that will be used to create the function. For
example, to create a debuggable function, the following statement could be
included:
SET OPTION DBGVIEW = *SOURCE
For
more information, see SET OPTION.
The options CLOSQLCSR,
CNULRQD, COMPILEOPT, NAMING, and SQLCA are not allowed in the CREATE FUNCTION
statement.
- SQL-routine-body
- Specifies a single SQL statement, including a compound statement. See SQL control statements for more information about defining SQL functions.
A call to a procedure that issues a CONNECT, SET CONNECTION, RELEASE, DISCONNECT,
COMMIT, ROLLBACK and SET TRANSACTION statement is not allowed in a function.
If the SQL-routine-body is a compound statement, it must contain
exactly one RETURN statement and it must be executed when the function is
called.
General considerations for defining user-defined functions: See CREATE FUNCTION for general information on defining user-defined
functions.
Function ownership: If SQL names were
specified:
- If a user profile with the same name as the schema into which the function
is created exists, the owner of the function is that
user profile.
- Otherwise, the owner of the function is the user
profile or group user profile of the job executing the statement.
If system names were specified, the owner of the
function is the user profile or group user profile of the job executing the
statement.
Function authority: If SQL names are used, functions
are created with the system authority of *EXCLUDE on *PUBLIC. If system names
are used, functions are created with the authority to *PUBLIC as determined
by the create authority (CRTAUT) parameter of the schema.
If the owner of the function is a member of a group profile (GRPPRF keyword)
and group authority is specified (GRPAUT keyword), that group profile will
also have authority to the function.
Creating the function: When an SQL function is created, the database manager creates
a temporary source file that will contain C source code with embedded SQL
statements. A *SRVPGM object is then created using the CRTSRVPGM command.
The SQL options used to create the service program are the options that are
in effect at the time the CREATE FUNCTION statement is executed. The service
program is created with ACTGRP(*CALLER).
The specific name is used to determine the name of the source file member
and *SRVPGM object. If the specific name is a valid system name, it will used
as the name of member and program. If the member already exists, it will be
overlaid. If a program already exists in the specified library, a unique name
is generated using the rules for generating system table names. If the specific
name is not a valid system name, a unique name is generated using the rules
for generating system table names.
The function's attributes are saved in the associated service program object.
If the *SRVPGM object is saved and then restored to this or another system,
the catalogs are automatically updated with those attributes.
During restore of the function:
- If the specific name was specified when the function was originally created
and it is not unique, an error is issued.
- If the specific name was not specified, a unique name is generated if
necessary.
- If the same function signature already exists in the catalog:
- If the name of the service program is the same as the one registered in
the catalog, the function information in the catalog will be replaced.
- Otherwise, the function cannot be registered, and an error is issued.
Identifier resolution: If the tables specified in
a routine body exist, all references in the routine body of an SQL routine
are resolved to identify a particular column, SQL parameter, or SQL variable
at the time the SQL routine is created. If the tables do not exist, all names
that exist as SQL variables or parameters are resolved to identify the variable
or parameter when the function is created. The remaining names are assumed
to be columns bound to the tables when the function is invoked.
If duplicate names are used for columns and SQL variables and parameters,
qualify the duplicate names by using the table designator for columns, the
function name for parameters, and the label name for SQL variables.
Invoking the function: When an SQL function is invoked,
it runs in the activation group of the calling program.
Syntax alternatives: The following keywords are synonyms
supported for compatibility to prior releases. These keywords are non-standard
and should not be used:
- The keywords VARIANT and NOT VARIANT can be used as synonyms for NOT DETERMINISTIC
and DETERMINISTIC.
- The keywords NULL CALL and NOT NULL CALL can be used as synonyms for CALLED
ON NULL INPUT and RETURNS NULL ON NULL INPUT.
- The keywords IS DETERMINISTIC may be used as a synonym for DETERMINISTIC.
Define a table function that returns the employees in a specified department
number.
CREATE FUNCTION DEPTEMPLOYEES (DEPTNO CHAR(3))
RETURNS TABLE (EMPNO CHAR(6),
LASTNAME VARCHAR(15),
FIRSTNAME VARCHAR(12))
LANGUAGE SQL
READS SQL DATA
NO EXTERNAL ACTION
DETERMINISTIC
DISALLOW PARALLEL
RETURN
SELECT EMPNO,LASTNAME,FIRSTNME
FROM EMPLOYEE
WHERE EMPLOYEE.WORKDEPT =DEPTEMPLOYEES.DEPTNO
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