SQL Deadlock

Why SQL Deadlock is important

-- Create a sample table
CREATE TABLE Orders (
    OrderID INT PRIMARY KEY,
    CustomerID INT,
    OrderDate DATE,
    OrderStatus VARCHAR(20)
);

-- Insert some sample data
INSERT INTO Orders (OrderID, CustomerID, OrderDate, OrderStatus)
VALUES
(1, 101, '2023-10-26', 'Pending'),
(2, 102, '2023-10-25', 'Shipped'),
(3, 101, '2023-10-27', 'Processing');

-- Declare a cursor to iterate through orders placed before 2023-10-26
DECLARE OrderCursor CURSOR FOR
SELECT OrderID, OrderStatus
FROM Orders
WHERE OrderDate < '2023-10-26';

-- Declare variables to hold the retrieved data
DECLARE @OrderID INT;
DECLARE @OrderStatus VARCHAR(20);

-- Open the cursor
OPEN OrderCursor;

-- Fetch the first row
FETCH NEXT FROM OrderCursor INTO @OrderID, @OrderStatus;

-- Loop through the rows
WHILE @@FETCH_STATUS = 0
BEGIN
    -- Update the order status to 'Shipped'
    UPDATE Orders SET OrderStatus = 'Shipped' WHERE OrderID = @OrderID;
    -- Fetch the next row
    FETCH NEXT FROM OrderCursor INTO @OrderID, @OrderStatus;
END;

-- Close and deallocate the cursor
CLOSE OrderCursor;
DEALLOCATE OrderCursor;

SELECT * FROM Orders;