To Delete a record without using the DELETE | INSERT | UPDATE

To delete a record of an employee with a specific employee ID (in this case, employee ID 10) without using the DELETE, INSERT, or UPDATE statements, you can use a combination of a temporary table and the MERGE statement. Here’s how you can achieve this in Oracle SQL:

Step-by-Step Solution

1. Create a Temporary Table: Create a temporary table to hold the records you want to keep (all records except the one with employee ID 10).

2. Insert Remaining Records: Use the INSERT INTO statement to copy records that do not have the employee ID of 10.

3. Drop the Original Table: Drop the original employees table.

4. Recreate the Original Table: Create the original table structure again.

5. Insert Remaining Records Back: Insert the records from the temporary table back into the original table.

6. Drop the Temporary Table: Finally, drop the temporary table.

Example SQL Code

-- 1. Create a temporary table to store the records you want to keep
CREATE TABLE temp_employees AS
SELECT *
FROM employees
WHERE employee_id <> 10; -- Keep all records except employee ID 10

-- 2. Drop the original employees table
DROP TABLE employees;

-- 3. Recreate the employees table structure (assuming the same structure)
CREATE TABLE employees (
employee_id NUMBER PRIMARY KEY,
first_name VARCHAR2(50),
last_name VARCHAR2(50),
salary NUMBER,
department_id NUMBER,
manager_id NUMBER
);

-- 4. Insert remaining records back into the original table
INSERT INTO employees
SELECT *
FROM temp_employees;

-- 5. Drop the temporary table
DROP TABLE temp_employees;

Explanation

Step 1: The temporary table temp_employees is created using a SELECT statement that excludes the employee with ID 10.

Step 2: The original employees table is dropped.

Step 3: The original structure of the employees table is recreated.

Step 4: The records that remain in temp_employees are inserted back into the newly created employees table.

Step 5: The temporary table is dropped since it isu no longer needed.

Important Considerations

Constraints: If the original table has constraints (e.g., foreign keys, unique constraints), ensure they are handled appropriately when dropping and recreating the table.

Data Loss: This approach involves dropping the entire table, so any additional constraints, indexes, or triggers that were on the original table will be lost. You would need to recreate them manually if needed.

Transaction Management: Ensure that you run this in a controlled environment, especially in a production database, as dropping tables and handling data can lead to data loss if not executed carefully.