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Create Scalar User Defined Functions

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Create Scalar User Defined Functions
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Create Scalar User Defined Functions

July 17, 2020
Created by
September 5, 2016
Leveraging SQLScript in Stored Procedures, User Defined Functions, and User Defined Libraries

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


Step 1: Create New Function

Create a new folder called functions under the src folder by right clicking on the src folder and choosing New, then Folder.

New Function

Right click on the functions folder and choose New, then Function.

New Function

Enter the name of the file as get_full_name and click Create.

create
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Step 2: Edit the Function and Save

The editor will open with a small code snippet inserted

code snippet

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

save
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Step 3: Edit Procedure

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.

rename

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.

Change select

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;

END
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Step 4: Save, Build and Check Results

Click 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.

Results
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Next Steps

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