This CREATE FUNCTION (External Table) statement defines an external table function at the current server. The function returns a result table.
An external user-defined table function may be used in the FROM clause of a subselect, and returns a table to the subselect by returning one row each time it is invoked.
This statement can be embedded in an application program or issued 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:
If the external program or service program exists, the privileges held by the authorization ID of the statement must include at least one of the following:
If SQL names are specified and a user profile exists that has the same name as the library into which the function is created, and that name is different from the authorization ID of the statement, then the privileges held by the authorization ID of the statement must include at least one of the following:
If a distinct type is referenced, the privileges held by the authorization ID of the statement must include at least one of the following:
To replace an existing function, the privileges
held by the authorization ID of the statement must include at least
one of the following:

The system authority *READ to the SYSFUNCS catalog
view and SYSPARMS catalog table
For information about 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--------------> '-OR REPLACE-' >--(--+---------------------------+--)--------------------------> | .-,---------------------. | | V | | '---parameter-declaration-+-' .-,---------------------------------------. V | >--RETURNS TABLE--(----column-name--data-type2--+------------+-+--)--> '-AS LOCATOR-' >--option-list-------------------------------------------------><
parameter-declaration |--+----------------+--data-type1--+-----------------------+----| '-parameter-name-' '-AS -+-LOCATOR-------+-' '-XML-cast-type-' data-type1, data-type2 |--+-built-in-type------+---------------------------------------| '-distinct-type-name-' XML-cast-type .-(--1--)-------. |--+-+-+-CHARACTER-+--+---------------+--+--------------+-----------------------------------------------+-+--| | | '-CHAR------' '-(--integer--)-' '-ccsid-clause-' | | | +-+-+-CHARACTER-+--VARYING-+--(--integer--)--+--------------+--------------------------------------+ | | | | '-CHAR------' | '-ccsid-clause-' | | | | '-VARCHAR----------------' | | | | .-(--1M--)-------------. | | | '-----+-+-CHARACTER-+--LARGE OBJECT-+------+----------------------+--+--------------+--+---------+-' | | | '-CHAR------' | '-(--integer--+---+--)-' '-ccsid-clause-' '-LOCATOR-' | | '-CLOB------------------------' +-K-+ | | +-M-+ | | '-G-' | | .-(--1--)-------. | +-+---GRAPHIC----+---------------+--+--------------+--------------------+------------------------------+ | | '-(--integer--)-' '-ccsid-clause-' | | | +-+-GRAPHIC VARYING-+--(--integer--)--+--------------+----------------+ | | | '-VARGRAPHIC------' '-ccsid-clause-' | | | | .-(--1M--)-------------. | | | '---DBCLOB----+----------------------+--+--------------+--+---------+-' | | '-(--integer--+---+--)-' '-ccsid-clause-' '-LOCATOR-' | | +-K-+ | | +-M-+ | | '-G-' | | .-(--1--)-------. | '-+-+-BINARY--+---------------+---------+------------------------------+-------------------------------' | | '-(--integer--)-' | | | '-+-BINARY VARYING-+--(--integer--)-' | | '-VARBINARY------' | | .-(--1M--)-------------. | '---+-BLOB----------------+----+----------------------+--+---------+-' '-BINARY LARGE OBJECT-' '-(--integer--+---+--)-' '-LOCATOR-' +-K-+ +-M-+ '-G-'
built-in-type |--+-+---SMALLINT---+-------------------------------------------------------------------------------------+--| | +-+-INTEGER-+--+ | | | '-INT-----' | | | '---BIGINT-----' | | .-(5,0)------------------------. | +-+-+-DECIMAL-+-+--+------------------------------+----------------------------------------------------+ | | '-DEC-----' | | .-,0--------. | | | '-+-NUMERIC-+-' '-(--integer--+-----------+--)-' | | '-NUM-----' '-, integer-' | | .-(--53--)------. | +-+-FLOAT--+---------------+-+-------------------------------------------------------------------------+ | | '-(--integer--)-' | | | +-REAL---------------------+ | | | .-PRECISION-. | | | '-DOUBLE--+-----------+----' | | .-(--34--)-. | +---DECFLOAT--+----------+-----------------------------------------------------------------------------+ | '-(--16--)-' | | .-(--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--)-------. | +-+-+-+-NATIONAL CHARACTER-+--+---------------+----------+---------------------+--+------------------+-+ | | | +-NATIONAL CHAR------+ '-(--integer--)-' | | '-normalize-clause-' | | | | '-NCHAR--------------' | | | | | '-+-+-NATIONAL CHARACTER-+--VARYING-+--(--integer--)-' | | | | | +-NATIONAL CHAR------+ | | | | | | '-NCHAR--------------' | | | | | '-NVARCHAR------------------------' | | | | .-(--1M--)-------------. | | | '-----+-+-NATIONAL CHARACTER-+--LARGE OBJECT-+------+----------------------+-' | | | '-NCHAR--------------' | '-(--integer--+---+--)-' | | '-NCLOB--------------------------------' +-K-+ | | +-M-+ | | '-G-' | | .-(--1--)-------. | +-+-+-BINARY--+---------------+---------+-----------------+--------------------------------------------+ | | | '-(--integer--)-' | | | | | '-+-BINARY VARYING-+--(--integer--)-' | | | | '-VARBINARY------' | | | | .-(--1M--)-------------. | | | '---+-BLOB----------------+----+----------------------+-' | | '-BINARY LARGE OBJECT-' '-(--integer--+---+--)-' | | +-K-+ | | +-M-+ | | '-G-' | +-+-DATE-------------------+---------------------------------------------------------------------------+ | | .-(--0--)-. | | | +-TIME--+---------+------+ | | | .-(--6--)-. | | | '-TIMESTAMP--+---------+-' | +---ROWID----------------------------------------------------------------------------------------------+ '---XML--+------------------+--------------------------------------------------------------------------' | (1) | '-ccsid-clause-----' ccsid-clause |--CCSID--integer--+------------------+-------------------------| '-normalize-clause-' normalize-clause .-NOT NORMALIZED-. |--+-NORMALIZED-----+-------------------------------------------|
option-list (1) |--+-----------------------+------------------------------------> '-LANGUAGE--+-C-------+-' +-C++-----+ +-CL------+ +-COBOL---+ +-COBOLLE-+ +-JAVA----+ +-PLI-----+ +-RPG-----+ '-RPGLE---' >--+-PARAMETER STYLE SQL--------+-------------------------------> '-PARAMETER STYLE DB2GENERAL-' .-NOT DETERMINISTIC . >--+-------------------------+--+------------------------+------> '-SPECIFIC--specific-name-' '-DETERMINISTIC----------' .-READS SQL DATA----. .-CALLED ON NULL INPUT ------. >--+-------------------+--+----------------------------+--------> +-NO SQL------------+ '-RETURNS NULL ON NULL INPUT-' +-CONTAINS SQL------+ '-MODIFIES SQL DATA-' .-INHERIT SPECIAL REGISTERS-. .-STATIC DISPATCH-. >--+---------------------------+--+-----------------+-----------> .-NO DBINFO . .-EXTERNAL ACTION----. .-FENCED-----. >--+-----------+--+--------------------+--+------------+--------> '-DBINFO----' '-NO EXTERNAL ACTION-' '-NOT FENCED-' .-NO FINAL CALL-. >--+-------------------+--+---------------+---------------------> +-PROGRAM TYPE MAIN-+ '-FINAL CALL----' '-PROGRAM TYPE SUB--' .-NO SCRATCHPAD-----------. >--+-------------------+--+-------------------------+-----------> +-ALLOW PARALLEL----+ | .-100-----. | '-DISALLOW PARALLEL-' '-SCRATCHPAD--+---------+-' '-integer-' .-EXTERNAL-----------------------------. >--+--------------------------------------+---------------------> '-EXTERNAL NAME--external-program-name-' >--+---------------------+--------------------------------------| '-CARDINALITY--bigint-'
OR REPLACE
Specifies to replace the definition
for the function if one exists at the current server. The existing
definition is effectively dropped before the new definition is replaced
in the catalog with the exception that privileges that were granted
on the function are not affected. This option is ignored if a definition
for the function does not exist at the current server. To replace
an existing function, the specific-name and function-name of
the new definition must be the same as the specific-name and function-name of
the old definition, or the signature of the new definition must match
the signature of the old definition. Otherwise, a new function is
created.
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:
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.
If the name of the distinct type is unqualified, the database manager resolves the schema name by searching the schemas in the SQL path.
Parameters with a large object (LOB) data type are not supported when PARAMETER STYLE JAVA is specified.
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.
Any parameter
that has an XML type must specify either the XML-cast-type clause
or the AS LOCATOR clause.
LOB or
XML data type or a distinct type based on a LOB or XML data type
.
If AS LOCATOR is specified, FOR SBCS DATA or FOR MIXED DATA must
not be specified.For more information on the AS LOCATOR clause, see Specifying AS LOCATOR for a parameter.
AS XML-cast-type
Specifies the data type passed to the function for a parameter
that is XML type or a distinct type based on XML type. If LOCATOR
is specified, the parameter is a locator to the value rather than
the actual value.
If a CCSID value is specified, only
Unicode CCSID values can be specified for graphic data types. If a
CCSID value is not specified, the CCSID is established at the time
the function is created according to the SQL_XML_DATA_CCSID QAQQINI
option setting. The default CCSID is 1208. See XML Values for a description of this option.

Assume that the number of parameters is n. For PARAMETER STYLE DB2GENERAL, there must be no more than (255-(n*2))/2 columns. For PARAMETER STYLE SQL, there must be no more than (247-(n*2))/2 columns.
You can specify any built-in data type (except LONG VARCHAR, LONG VARGRAPHIC, or DataLink) or a distinct type (that is not based on a DataLink).
If a DATE or TIME is specified, the table function must return the date or time in ISO format.
If a CCSID is specified,
If a CCSID is not specified,
LOB or XML data
type or a distinct type based on a LOB or XML data type
. If
AS LOCATOR is specified, FOR SBCS DATA or FOR MIXED DATA must not
be specified.For more information on the AS LOCATOR clause, see Specifying AS LOCATOR for a parameter.
If LANGUAGE is not specified, the LANGUAGE is determined from the program attribute information associated with the external program at the time the function is created. The language of the program is assumed to be C if:
DB2GENERAL is only allowed when the LANGUAGE is JAVA.
The user may set the SQLSTATE to any valid value in the external program to return an error or warning from the function.
Note that the language of the external function determines how the parameters are passed. For example, in C, any VARCHAR or CHAR parameters are passed as NUL-terminated strings. For more information, see the SQL Programming topic collection. For Java routines, see the IBM® Developer Kit for Java topic collection.
The default is READS SQL DATA.
| Field | Data Type | Description |
|---|---|---|
| Relational database | VARCHAR(128) | The name of the current server. |
| Authorization ID | VARCHAR(128) | The run-time authorization ID. |
| CCSID Information | INTEGER
INTEGER
INTEGER
INTEGER
CHAR(8) |
The CCSID information of the job.
Three sets of three CCSIDs are returned. The following information
identifies the three CCSIDs in each set:
Each set of CCSIDs is for a different encoding scheme (EBCDIC, ASCII, and Unicode). If a CCSID is not explicitly specified for a parameter on the CREATE FUNCTION statement, the input string is assumed to be encoded in the CCSID of the job at the time the function is executed. If the CCSID of the input string is not the same as the CCSID of the parameter, the input string passed to the external function will be converted before calling the external program. |
| Target column | VARCHAR(128) VARCHAR(128) VARCHAR(128) |
If a user-defined function is specified
on the right-hand side of a SET clause in an UPDATE statement, the
following information identifies the target column:
|
| Version and release | CHAR(8) | The version, release, and modification level of the database manager. |
| Platform | INTEGER | The server's platform type. |
| Number of table function column list entries | SMALLINT | The number of non-zero entries in the table function column list specified in the "Table function column list" field below. |
| Reserved | CHAR(24) | Reserved for future use. |
| Table function column list | Pointer (16 Bytes) | This field is a pointer to an array
of short integers which is dynamically allocated by the database manager.
Only the first n entries, where n is specified in the "Number of table
function column list entries" field, are of interest, n may be equal
to 0, and is less than or equal to the number of result columns defined
for the function in the RETURNS TABLE clause. The values correspond
to the ordinal numbers of the columns which this statement needs from
the table function. A value of 1 means the first defined result column,
2 means the second defined result column, and so on. The values may
be in any order. Note that n could be equal to zero for a statement
that is similar to SELECT COUNT(*) FROM TABLE(TF(...)) AS QQ, where
no actual column values are needed by the query. This array represents an opportunity for optimization. The function need not return all values for all the result columns of the table function. Only a subset of the values may be needed in a particular context, and these are the columns identified (by number) in the array. Since this optimization may complicate the function logic, the function can choose to return every defined column. |
NO EXTERNAL ACTION functions might perform better than EXTERNAL ACTION functions because they might not be invoked for each successive function invocation.
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 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.
With NO FINAL CALL, the database manager will only make three types of calls to the table function: open, fetch and close. However, if FINAL CALL is specified, then in addition to open, fetch and close, a first call and a final call can be made to the table function.
A final call enables the function to free any system resources that it has acquired. A final call is useful when the function has been defined with the SCRATCHPAD keyword and the function acquires system resources and stores them in the scratchpad. The default is NO FINAL CALL.
The types of calls are:
A final call occurs at these times:
If a commit operation occurs while a cursor defined as WITH HOLD is open, a final call is made when the cursor is closed or the application ends.
Commitable operations should not be performed during a FINAL CALL, because the FINAL CALL may occur during a close invoked as part of a COMMIT operation.
The default is DISALLOW PARALLEL if one or more of the following clauses are specified: NOT DETERMINISTIC, EXTERNAL ACTION, FINAL CALL, MODIFIES SQL DATA, or SCRATCHPAD. Otherwise, ALLOW PARALLEL is the default.
See the descriptions of NOT DETERMINISTIC, EXTERNAL ACTION, MODIFIES SQL DATA, SCRATCHPAD, and FINAL CALL for considerations that apply to specification of ALLOW PARALLEL.
SELECT A.C1, B.C1 FROM TABLE(UDFX(:hv1)) AS A, TABLE(UDFX(:hv1)) AS B
If external-program-name is not specified, the external program name is assumed to be the same as the function name.
COMMENT, GRANT, LABEL, or REVOKE
operations
are performed on the function.The validity of the name is checked at the application server. If the format of the name is not correct, an error is returned.
The program, service program, or Java class need not exist at the time the function is created, but it must exist at the time the function is invoked.
CONNECT, SET CONNECTION, RELEASE, DISCONNECT, COMMIT, ROLLBACK, and SET TRANSACTION statements are not allowed in the external program of the function.
A table function that returns a row every time it is called and never returns the end-of-table condition has infinite cardinality. A query that invokes such a function and requires an eventual end-of-table condition before it can return any data will not return unless interrupted. Table functions that never return the end-of-table condition should not be used in queries involving DISTINCT, GROUP BY, or ORDER BY.
General considerations for defining user-defined functions: See CREATE FUNCTION for general information about defining user-defined functions.


Creating the function: When an external function associated with an ILE external program or service program is created, an attempt is made to save the function's attributes in the associated program or service program object. If the *PGM or *SRVPGM object is saved and then restored to this or another system, the catalogs are automatically updated with those attributes.
The attributes can be saved for external functions subject to the following restrictions:
If system naming is specified and the external program name is not qualified, the external program must be found in the library list.
If the object cannot be updated, the function will still be created.
During restore of the function:
Invoking the function: When an external function is invoked, it runs in whatever activation group was specified when the external program or service program was created. However, ACTGRP(*CALLER) should normally be used so that the function runs in the same activation group as the calling program. ACTGRP(*NEW) is not allowed.
LANGUAGE JAVA functions always run in the default activation
group (*DFTACTGRP). Caution should be used when writing MODIFIES SQL
DATA Java functions. Since changes performed by the Java function
are performed in the default activation group, transaction problems
may occur if the invoker runs in a new activation group (*NEW).
Notes for Java functions: To be able to run Java functions, you must have the IBM Developer Kit for Java (5761-JV1) installed on your system. Otherwise, an SQLCODE of -443 will be returned and a CPDB521 message will be placed in the job log.
If an error occurs while running a Java function, an SQLCODE of -443 will be returned. Depending on the error, other messages may exist in the job log of the job where the function was run.
MODIFIES SQL DATA and EXTERNAL ACTION functions: If a MODIFIES SQL DATA or EXTERNAL ACTION function is invoked in other than the outermost select list, the results are unpredictable since the number of times the function is invoked will vary depending on the access plan used.
Syntax alternatives: The following keywords are synonyms supported for compatibility to prior releases. These keywords are non-standard and should not be used:
The following creates a table function written to return a row consisting of a single document identifier column for each known document in a text management system. The first parameter matches a given subject area and the second parameter contains a given string.
Within the context of a single session, the UDF will always return the same table, and therefore it is defined as DETERMINISTIC. Note the RETURNS clause which defines the output from DOCMATCH. FINAL CALL must be specified for each table function. Although the size of the output for DOCMATCH is highly variable, CARDINALITY 20 is a representative value, and is specified to help the optimizer.
CREATE FUNCTION DOCMATCH (VARCHAR(30), VARCHAR(255)) RETURNS TABLE (DOCID CHAR(16)) EXTERNAL NAME 'MYLIB/RAJIV(UDFMATCH)' LANGUAGE C PARAMETER STYLE SQL NO SQL DETERMINISTIC NO EXTERNAL ACTION NOT FENCED SCRATCHPAD FINAL CALL DISALLOW PARALLEL CARDINALITY 20