I'm working with GridDB and have encountered an error that I'm struggling to resolve. The error message is:
305009 SQL_PROC_MULTIPLE_TUPLE ERROR SQL execution failed. Data operation may be duplicated. Check that multiple rows are not selected in places where only up to a single row is selected, as in a scalar subquery.
I suspect the issue is related to a scalar subquery in my SQL query. Here's a simplified version of the code I'm working with:
CREATE TABLE Orders (
order_id INTEGER,
customer_id INTEGER,
amount DOUBLE
);
CREATE TABLE Customers (
customer_id INTEGER,
customer_name STRING
);
INSERT INTO Orders (order_id, customer_id, amount) VALUES (1, 101, 250.00);
INSERT INTO Orders (order_id, customer_id, amount) VALUES (2, 102, 150.00);
INSERT INTO Orders (order_id, customer_id, amount) VALUES (3, 101, 300.00);
INSERT INTO Customers (customer_id, customer_name) VALUES (101, 'Alice');
INSERT INTO Customers (customer_id, customer_name) VALUES (102, 'Bob');
-- Attempting to use a scalar subquery to get the customer name for each order
SELECT order_id, amount,
(SELECT customer_name FROM Customers WHERE Customers.customer_id = Orders.customer_id) AS customer_name
FROM Orders;
In this query, I'm trying to retrieve the customer_name for each order using a scalar subquery. However, it seems to be causing the error.
How can I modify the query to ensure that the scalar subquery returns only a single row? Are there any best practices for using scalar subqueries in GridDB to avoid this error? Is there an alternative approach to achieve the same result without encountering this error? Any guidance or suggestions would be greatly appreciated!