The support for user-defined procedures and functions, commonly known as stored procedures, makes NexusDB SQL a programmable database language, allowing users to automate tasks and extend the built-in functionality with custom routines.


NexusDB SQL supports user-defined procedures and functions written in SQL, called SQL routines, or hosted in a .NET assembly, called CLR routines (Enterprise Edition only). Since user-defined procedures and functions share many common characteristics and syntactic elements, they are both called SQL-invoked routines in standard SQL.


The procedure language in NexusDB adds power and flexibility to the functionality of user-defined procedures and functions written in SQL.



User-defined procedures


A user-defined procedure (UDP) can have both IN and OUT parameters. The OUT parameter is used to return a value from the procedure, and is equivalent to the result of a scalar-valued function. Procedures can also return a cursor by specifying a SELECT statement as the last statement in the routine body.


User-defined procedures are defined with the CREATE PROCEDURE statement and are invoked in SQL by the CALL statement.


The following example shows a procedure definition and how it is called in SQL:



// Parameter declarations with implicit IN mode

p_courseID SMALLINT,

p_courseName CHAR(20),

p_department CHAR(20),

p_numCredits TINYINT


MODIFIES SQL DATA -- We need write-access to update the courses table

// We prefer to use a compound statement in the routine body, even with a single statement



VALUES ( p_courseID, p_courseName, p_department, p_numCredits );



CALL addCourse( :courseID, :courseName, :department, :numCredits );



User-defined functions


Like functions in traditional programming languages, a user-defined function (UDF) always returns a value. The function result can be either a scalar value (scalar-valued function) or a table derived from a cursor specification (table-valued function), by specifying TABLE in the RETURNS clause of the function definition. A scalar-valued function can be referenced everywhere in SQL a scalar value is expected, while a table-valued function can be referenced in the FROM clause of a SELECT statement or invoked by calling the function as a separate SQL statement.


User-defined functions are defined with the CREATE FUNCTION statement and are invoked in SQL by the function name, see routine invocation.


The following example shows a function definition and how it is invoked in SQL:


CREATE FUNCTION getFullName ( firstName VARCHAR(30), lastName VARCHAR(30) )



LANGUAGE SQL is implicit


CONTAINS SQL is implicit


RETURNS NULL ON NULL INPUT -- We don't invoke the function if any of the arguments are null

// Multiple statements in the routine body must appear inside a compound statement



SET name = firstName || ' ' || lastName;

RETURN name;



UPDATE students

SET studentName = getFullName( firstName, lastName )

WHERE studentID = 211;




Procedure Language

SQL-Invoked Routines

SQL Procedure Statements