HSQL SELECT Statement Not working - hsqldb

Question

I am new in HSQL. Tried a Procedure like below;
CREATE PROCEDURE GetData(ObjectId VARCHAR(36)) READS SQL DATA
DYNAMIC RESULT SETS 1
BEGIN ATOMIC
DECLARE MaxVal NUMERIC(19,2);
DECLARE MinVal NUMERIC(19,2);
DECLARE BiggestObjectName VARCHAR(50);
DECLARE SmallestObjectName VARCHAR(50);
SET MaxVal = (SELECT MAX(HeightValue) FROM ObjectData WHERE ObjectId=ObjectId);
SET MinVal = (SELECT MIN(HeightValue) FROM ObjectData WHERE ObjectId=ObjectId);
SET BiggestObjectName = (SELECT ObjectName FROM ObjectData WHERE ObjectId=ObjectId AND HeightValue=MaxVal);
SET SmallestObjectName = (SELECT ObjectName FROM ObjectData WHERE ObjectId=ObjectId AND HeightValue=MinVal);
if MaxVal IS NOT NULL THEN
DECLARE result CURSOR WITH RETURN FOR
SELECT MaxVal AS MaximumHeight, MinVal AS MinimumHeight, BiggestObjectName AS LargestDisplayCaseName, SmallestObjectName AS SmallestDisplayCaseName FOR READ ONLY;
OPEN result;
END
But i get error;
Caused by: java.sql.SQLSyntaxErrorException: unexpected token: ; required: INTO
Is it not the correct syntax?
Any help is appreciated :)

Answer 1

There are several things wrong with your stored procedure. For one I don't think you can declare a cursor as part of an IF statement.
Assignment of a variable needs to be either using select ... into or you need to put the select statement between parentheses:
SET MaxVal = (SELECT MAX(HeightValue) FROM ObjectData WHERE ObjectId=ObjectId);
SET ObjectName = (SELECT ObjectName FROM ObjectData WHERE ObjectId=ObjectId AND HeightValue=MaxVal);
or
SELECT MAX(HeightValue)
into maxval
FROM ObjectData
WHERE ObjectId=ObjectId;
You also can't use = or <> to compare NULL values. if MaxVal != NULL THEN needs to be
if maxval is not null then
...
end if; --<< you also forgot the `end if`
You also can't use a SELECT statement without a FROM clause, and I don't think you can define a cursor that only selects values from variables in HSQLDB.
But don't need the intermediate selects anyway, you can do that in a single select:
CREATE PROCEDURE GetData(ObjectId VARCHAR(36)) READS SQL DATA
DYNAMIC RESULT SETS 1
BEGIN ATOMIC
DECLARE result CURSOR FOR
select o1.heightvalue as maximumheight, o1.objectname as displaycasename
from objectdata o1
where objectid = 'one'
and heightvalue = (select max(heightvalue)
from objectdata o2
where o2.objectid = o1.objectid);
OPEN result;
END;

Answer 2

You are not using the correct syntax to create the procedure. According to the syntax you have to put the value(s) selected from table into a local variable(s). Follow the following example.
CREATE PROCEDURE get_customer(IN id INT, OUT firstname VARCHAR(50), OUT lastname VARCHAR(50))
READS SQL DATA
BEGIN ATOMIC
-- this statement uses the id to get firstname and lastname
SELECT first_name, last_name INTO firstname, lastname FROM customers WHERE cust_id = id;
END
I hope it'll help you.