Explanation: Using cteinsertstrategy with supported dialects
The cteinsertstrategy is a strategy that allows the usage of Common Table Expressions (CTEs) in insert statements. However, it can only be used with dialects that support CTEs that can take update or delete statements as well. This means that not all database management system (DBMS) dialects may support this strategy.
Example:
Let’s consider an example where we have a table named orders with columns order_id and order_date.
-- Create the 'orders' table
CREATE TABLE orders (
order_id INT,
order_date DATE
);
-- Insert sample data
INSERT INTO orders (order_id, order_date) VALUES (1, '2022-01-01');
INSERT INTO orders (order_id, order_date) VALUES (2, '2022-02-01');
INSERT INTO orders (order_id, order_date) VALUES (3, '2022-03-01');
-- Using cteinsertstrategy with an update statement
WITH cte_update AS (
UPDATE orders SET order_date = '2022-04-01' WHERE order_id = 1
)
INSERT INTO orders (order_id, order_date)
SELECT order_id + 10, order_date
FROM cte_update;
-- Using cteinsertstrategy with a delete statement
WITH cte_delete AS (
DELETE FROM orders WHERE order_id = 2
)
INSERT INTO orders (order_id, order_date)
SELECT order_id + 20, order_date
FROM cte_delete;
In the above example, we first create the orders table and insert some sample data. Then, we utilize the cteinsertstrategy in combination with update and delete statements.
With the update statement, we first update the order with order_id = 1 to set the order_date to ‘2022-04-01’. Then, using the CTE cte_update, we insert a new row into the orders table with an incremented order_id (original order_id + 10) and the same order_date from the update.
Similarly, with the delete statement, we first delete the order with order_id = 2. Then, using the CTE cte_delete, we insert a new row into the orders table with an incremented order_id (original order_id + 20) and the same order_date from the delete.