Creates a new stored user-defined function.
function-nameshould follow the normal rules for naming database objects, see Naming Objects.
function-nameis specified in its unqualified form, the function will be created in the schema which has the same name as the current ident.
function-nameis specified in its fully qualified form (i.e.
schema-name.function-name) the function will be created in the named schema (in this case, the current ident must be the creator of the specified schema).
The fully qualified function name must be used by all idents except the ident that has the same name as the schema to which the function belongs.
It is possible to create multiple functions with the same name if they differ with regard to either the number of parameters or the data type for the parameter. It is not possible to have multiple functions that only differ with regard to the return data type. See Mimer SQL Programmer's Manual, Parameter Overloading for more information. Type precedence lists are found in Type Precedence Lists.
Each function can be given a specific name, which must be unique within a schema. If no specific name is given, the system will generate a unique name. The specific name for a function can be retrieved by using the
A specific name can be used in
REVOKEstatements. It is particularly useful when dealing with function with parameter overloading. Instead of having to specify a list of data types, in order to distinguish the function, the specific name can be used.
parameter-nameshould follow the normal rules for naming SQL identifiers, see SQL Identifiers.
The permitted values for
data-typeare described in Data Types in SQL Statements.
NOT DETERMINISTICis specified, then
NOT DETERMINISTICis implicit.
DETERMINISTICis specified, then the function is guaranteed to produce the same result every time it is invoked with the same set of input values and repeated invocations of it can, therefore, be optimized.
The following access options may be specified:
The function may not contain any data-manipulation-statements. All other
procedural-sql-statementsare permitted. The function may only invoke
CONTAINS SQLfunctions and procedures. This option effectively prevents a routine from performing read or write operations on data in the database.
READS SQL DATA
MODIFIES SQL DATA
READS SQL DATAnor
MODIFIES SQL DATAis specified, then
CONTAINS SQLis implicit.
A function created this way cannot be added to a module.
It is possible to create multiple functions with the same name in a schema if the functions have a different number of parameters or parameters with different data types. It is not possible to have multiple functions that only differs with respect to the return data type.
It is not possible to create a synonym for a function name.
A parameter name must be unique within the function.
The parameter mode cannot be specified for a function parameter (as it is for a procedure parameter).
The ROW data type cannot be specified in
DETERMINISTICis specified, the procedural SQL statement of the function may not contain, or be, a reference to:
LOCALTIMESTAMPand the function may not invoke functions or procedures that are not deterministic.
If an invoked function attempts to execute a
ROLLBACKstatement in a context where this is not permitted, (i.e. after being invoked from within a result set procedure, from within an atomic compound statement or from a data manipulation statement in one of these contexts) an exception will be raised.
An ident must have
EXECUTEprivilege on the function in order to invoke it.
A function is invoked by specifying its name and parameter list where a value-expression would be used.
All function parameters have the default mode (which is IN). See CREATE PROCEDURE for details on the parameter modes.
parameter-namecan be the same as the name of the function, but this is not recommended.
Refer to the Mimer SQL User's Manual, Creating Functions, Procedures, Triggers and Modules for details on using the
CREATE FUNCTIONstatement in BSQL, where the
@delimiter is required.
ExamplesCREATE FUNCTION mimer_store_book.authors_name(p_name VARCHAR(48)) RETURNS VARCHAR(48) -- Formats a name into <surname>[,<initial>] DETERMINISTIC BEGIN DECLARE v_length, v_offset INTEGER; DECLARE v_fnm, v_name VARCHAR(48); SET v_length = POSITION(',' IN p_name); IF v_length = 0 THEN SET v_name = UPPER(TRIM(SUBSTRING(p_name FROM 1))); ELSE -- Append first initial to surname SET v_name = UPPER(TRIM(SUBSTRING(p_name FROM 1 FOR v_length))); SET v_fnm = UPPER(TRIM(SUBSTRING(p_name FROM v_length+1))); SET v_name = v_name || SUBSTRING(v_fnm FROM 1 FOR 1); END IF; RETURN v_name; END -- of routine mimer_store_book.authors_name
Example on how to create and use a simple function converting from to Celsius degrees from Fahrenheit degrees:CREATE FUNCTION C_from_F (Fdegrees integer) RETURNS integer RETURN CAST((Fdegrees - 32) * 5.0 / 9 + 0.5 AS integer); SELECT C_from_F(temperature) AS Celsius_degrees FROM US_Weather; SET ? = C_from_F(451);
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