用戶定義函數支持網站：本講大綱：1、創建和調用用戶定義函數2、用戶定義函數的刪除用戶定義函數用戶定義函數(UDF)：是用來擴展和增強

DB2內置函數提供的功能的特殊對象。用戶定義函數可以創建5種用戶定義函數：有源（或模板）函數SQL標量、表或行數外部標量函數

外部表函數OLE

DB外部表函數創建和調用用戶定義函數創建有源函數的基本語法是：Source_clause::=SOURCE

[source_function_name[source_datatype]|

SPECIFIC

source_specific_name][PARAMETER

CCSID

[ASCII

|

UNICODE]]as_template_clause

::=AS

TEMPLATE[NOT

DETERMINISTIC

|

DETERMINISTIC][NO

EXTERNAL

ACTION|

EXTERNAL

ACTION]創建和調用用戶定義函數CREATE

FUNCTION

function_name({parameter_name

input_datatype}[,…n])RETURNS

output_datatype[SPECIFIC

specific_name]<source_clause

|

as_template_clause>創建和調用SQL函數CREATE

FUNCTION

function_name({parameter_name

input_datatype}[,…n])RETURNS<output_datatype

|

TABLE

({column_name

column_datatype}[,…n]

|

ROW

({column_name column_datatype}

[,…n]))>[SPRCIFIC

specific_name]

[LANGUAGE

SQL][PARAMETER

CCSID

[ASCII

|

UNICODE]]

[DETERMINISTIC

|

NOT

DETERMINISTIC][EXTERNAL

ACTION

|

NO

EXTERNAL

ACTION][CONTAINS

SQL

|

READS

SQL

DATA

|

MODIFIES

SQL

DATA][STATIC

DISPATCH]

[CALLED

ON

NULL

INPUT]

[INHERIT

SPECIAL

REGISTERS][PREDICATES

(predicate_specification)][INHERIT

ISOLATION

LEVEL

<WITHOUT

|

WITH>

LOCK

REQUEST]SQL_function_body({pRE<o[,…[SP[PA[EX[COarameter_name

input_datatype}[,…n])TURNSutput_datatype

|

TABLE

({column_name

column_datatype}n]

|

ROW

({column_name column_datatype}

[,…n]))>RCIFIC

specific_name]

[LANGUAGE

SQL]RAMETER

CCSID

[ASCII

|

UNICODE]]

[DETERMINISTIC

|

NOT

DETTERNAL

ACTION

|

NO

EXTERNAL

ACTION]NTAINS

SQL

|

READS

SQL

DATA

|

MODIFIES

SQL

DATA][STATIC

DISPATCH]

[CALLED

ON

NULL

INPUT]

[INHERIT

SPECIAL

REGISTERS][PREDICATES

(predicate_specification)][INHERIT

ISOLATION

LEVEL

<WITHOUT

|

WITH>

LOCK

REQUEST]SQL_function_body創建SQL函數的主要語法是：pound_statement

::=CREATE

FUNCTION

function_[nlaambeel_name

:]

BEGIN

ATOMIC[local_variable_declaration

|SQL_function_bocdony

d::i=tion_declaration]RETURN

return_<stSaQteLm_eronut

t|ine_statement

|pound_statemednytnamic_coumpound_staEtReMmINeISnTItC>]END

[label_name]創建和調用SQL函數SELECT

column_list FROM

TABLE

([table_function_schema.]Table_function_name

(parameter_list))調用SQL函數的語法是：用戶定義函數的刪除使用界面刪除：用戶定義函數的刪除使用命令刪除：DROP

FUNCTION

function_name;或DROP

SPECIFIC

function

specific_function_name;參數說明：function_name：指要刪