Create Scalar User Defined Functions
Leveraging SQLScript in Stored Procedures, User Defined Functions, and User Defined Libraries
Overview
You will learn
- How to create a scalar UDF for generating a full name from the last, first and middle name of the employee
Prerequisites
Prerequisites
- This tutorial is designed for SAP HANA on premise and SAP HANA, express edition. It is not designed for SAP HANA Cloud.
- Tutorials: Intermediate Table Variables
Steps
Create a new folder called functions under the src folder by right clicking on the src folder and choosing New, then Folder.
Right click on the functions folder and choose New, then Function.
Enter the name of the file as get_full_name and click Create.
The editor will open with a small code snippet inserted
Enter the code into the editor as shown here. Please note the default for parameter im_employeeid which makes assigning a value to the parameter optional.
FUNCTION "get_full_name" (
IN im_firstname NVARCHAR(40) ,
IN im_middlename NVARCHAR(40),
IN im_lastname NVARCHAR(40),
IN im_employeeid NVARCHAR(10) DEFAULT '' )
RETURNS ex_fullname NVARCHAR(256) AS
BEGIN
if :im_middlename IS NULL THEN
ex_fullname = :im_lastname || ', ' || :im_firstname;
ELSE
ex_fullname = :im_lastname || ', ' ||
:im_firstname || ' ' || :im_middlename;
END IF;
IF :im_employeeid <> '' then
ex_fullname = :ex_fullname || '(' || :im_employeeid || ')';
END IF;
END;Click Save
Return to your procedure called get_po_header_data and modify it. Start by renaming the LOGINNAME column of the output table to FULLNAME. Also change the output length to 256. This is needed to match later on which the anticipated output structure.
Change the last SELECT statement. Remove the LOGINNAME column from the field list and replace it with a call to the scalar function that you created earlier. Make sure to pass the NAME.FIRST, NAME.MIDDLE and NAME.LAST name columns to the scalar function call.
The completed code should look very similar to this.
PROCEDURE "get_po_header_data" (
OUT EX_TOP_3_EMP_PO_COMBINED_CNT TABLE(
FULLNAME NVARCHAR(256),
CREATE_CNT INTEGER,
CHANGE_CNT INTEGER,
COMBINED_CNT INTEGER ) )
LANGUAGE SQLSCRIPT
SQL SECURITY INVOKER
--DEFAULT SCHEMA <default_schema_name>
READS SQL DATA AS
BEGIN
po_create_cnt = SELECT COUNT(*) AS CREATE_CNT, "HISTORY.CREATEDBY.EMPLOYEEID" AS EID
FROM "PO.Header" WHERE PURCHASEORDERID IN (
SELECT PURCHASEORDERID
FROM "PO.Item"
WHERE "PRODUCT.PRODUCTID" IS NOT NULL)
GROUP BY "HISTORY.CREATEDBY.EMPLOYEEID";
po_change_cnt = SELECT COUNT(*) AS CHANGE_CNT, "HISTORY.CHANGEDBY.EMPLOYEEID" AS EID
FROM "PO.Header" WHERE PURCHASEORDERID IN (
SELECT PURCHASEORDERID
FROM "PO.Item"
WHERE "PRODUCT.PRODUCTID" IS NOT NULL)
GROUP BY "HISTORY.CHANGEDBY.EMPLOYEEID";
EX_TOP_3_EMP_PO_COMBINED_CNT =
SELECT "get_full_name"( "NAME.FIRST", "NAME.MIDDLE", "NAME.LAST") as FULLNAME,
crcnt.CREATE_CNT, chcnt.CHANGE_CNT,
crcnt.CREATE_CNT + chcnt.CHANGE_CNT AS COMBINED_CNT
FROM "MD.Employees" as emp
LEFT OUTER JOIN :PO_CREATE_CNT AS crcnt
ON emp.EMPLOYEEID = crcnt.EID
LEFT OUTER JOIN :PO_CHANGE_CNT AS chcnt
ON emp.EMPLOYEEID = chcnt.EID
ORDER BY COMBINED_CNT DESC LIMIT 3;
ENDClick Save. Use what you have learned already and perform a build on your hdb module. Then return to the Database Explorer and generate a new CALL statement and run it. Notice the FULLNAME column, it shows the results of the scalar UDF logic.
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