Convert T-SQL Declare statement to SAP HANA - converters

Question

I cannot seem to get the query with declare statement working in SAP HANA. Below I've put the original working T-SQL version and the HANA version output from the SQL converter. I've tried several versions and combinations, but every time I get errors which you also find below. Anybody willing to give me an "how to" so I can copy this? I also spelled out the SAP Documentations, but nothing there what could help me.
Your help would be very appreciated.
The T-SQL Code:
DECLARE #NumAtCardDuplicate VARCHAR(50)
SET #NumAtCardDuplicate =
(SELECT TOP 1 DocNum
FROM TEST_RSCA.OPCH
WHERE CardCode = 'S100424'
AND NumAtCard = '118 120 266 805')
IF #NumAtCardDuplicate IS NOT NULL
SELECT 'Invoice number already used in entry ' + #NumAtCardDuplicate + '!'
ELSE
SELECT '118 120 266 805'
The translated HANA query:
NumAtCardDuplicate varchar(50);
SELECT
(SELECT TOP 1 "DocNum"
FROM TEST_RSCA.OPCH
WHERE "CardCode" = 'S100424'
AND "NumAtCard" = '118 120 266 805')
INTO NumAtCardDuplicate FROM DUMMY;
temp_var_0 integer;
SELECT :NumAtCardDuplicate INTO temp_var_0 FROM DUMMY;
IF :temp_var_0 IS NOT NULL THEN
SELECT 'Invoice number already used in entry ' || :NumAtCardDuplicate || '!'
FROM DUMMY;
ELSE
SELECT '118 120 266 805'
FROM DUMMY;
END IF;
The Errors I get:
Could not execute 'NumAtCardDuplicate varchar(50)' in 1 ms 989 µs .
SAP DBTech JDBC: [257]: sql syntax error: incorrect syntax near "NumAtCardDuplicate": line 1 col 1 (at pos 1)
Could not execute 'SELECT (SELECT TOP 1 "DocNum" FROM TEST_RSCA.OPCH WHERE "CardCode" ='S100424' AND "NumAtCard" = ...' in 3 ms 578 µs .
SAP DBTech JDBC: [337] (at 119): INTO clause not allowed for this SELECT statement: line 4 col 67 (at pos 119)
Could not execute 'temp_var_0 integer' in 1 ms 701 µs .
SAP DBTech JDBC: [257]: sql syntax error: incorrect syntax near "temp_var_0": line 1 col 1 (at pos 1)
Could not execute 'SELECT :NumAtCardDuplicate INTO temp_var_0 FROM DUMMY' in 1 ms 976 µs .
SAP DBTech JDBC: [467]: cannot use parameter variable: NUMATCARDDUPLICATE: line 4294967295 col 4294967295 (at pos 4294967295)
Could not execute 'IF :temp_var_0 IS NOT NULL THEN SELECT 'Invoice number already used in entry ' || ...' in 1 ms 560 µs .
SAP DBTech JDBC: [257]: sql syntax error: incorrect syntax near "IF": line 1 col 1 (at pos 1)
Could not execute 'ELSE SELECT '118 120 266 805' FROM DUMMY' in 1 ms 338 µs .
SAP DBTech JDBC: [257]: sql syntax error: incorrect syntax near "ELSE": line 1 col 1 (at pos 1)
SAP DBTech JDBC: [257]: sql syntax error: incorrect syntax near "END": line 1 col 1 (at pos 1)
Duration of 7 statements: 13 ms

Answer 1

I created a tables OPCH as shown below and inserted a row
create column table "SYSTEM"."OPCH"( "DOCNUM" VARCHAR (50) not null,
"CARDCODE" VARCHAR (7) null,
"NUMATCARD" VARCHAR (15) null,
primary key ("DOCNUM") )
insert into "SYSTEM"."OPCH" values('1','S100424','118 120 266 805');
Created a procedure with SQL Script as shown below
CREATE PROCEDURE SYSTEM.Z_CARDDUPLICATE LANGUAGE SQLSCRIPT
AS
BEGIN
declare NumAtCardDuplicate varchar2(50);
SELECT TOP 1 DocNum
INTO NumAtCardDuplicate
FROM SYSTEM.OPCH
WHERE CardCode = 'S100424'
AND NumAtCard = '118 120 266 805';
IF :NumAtCardDuplicate IS NOT NULL THEN
SELECT 'Invoice number already used in entry ' || :NumAtCardDuplicate || '!'
FROM DUMMY;
ELSE
SELECT '118 120 266 805'
FROM DUMMY;
END IF;
End
Called the procedure from SQL Console
CALL SYSTEM.Z_CARDDUPLICATE;
It works. Result is "Invoice number already used in entry 1!"
Statement 'CALL SYSTEM.Z_CARDDUPLICATE'
successfully executed in 132 ms 11 µs (server processing time: 29 ms 588 µs)
Fetched 1 row(s) in 0 ms 10 µs (server processing time: 0 ms 0 µs)
Let me know if this does not work for you.

Answer 2

To execute SQLScript on SQL Console, you are not required to create procedures any more in fact
Simply surround your SQL code between DO BEGIN ... END; clause as follows
do begin
declare NumAtCardDuplicate varchar(50);
SELECT TOP 1 DocNum
INTO NumAtCardDuplicate
FROM KODYAZ.OPCH
WHERE CardCode = 'S100424'
AND NumAtCard = '118 120 266 805';
IF :NumAtCardDuplicate IS NOT NULL THEN
SELECT 'Invoice number already used in entry ' || :NumAtCardDuplicate || '!'
FROM DUMMY;
ELSE
SELECT '118 120 266 805'
FROM DUMMY;
END IF;
end;
Please note that I used the same code block that Reddy has suggested to use