UPDATE and DELETE

It's time to get back to writing queries and consider two more statements.

You already know how to clear a table, add a column, insert data, etc. But for proper interaction with the database, we need to understand how to update and delete individual rows.

For this, there are two statements and types of queries: the UPDATE and the DELETE queries.

Let's look at an example with the medications table:

Let's imagine we need to update the price for a specific type of medication. For example, currently, there's a 50% discount on ibuprofen, and we need to change the price for this product.

Our UPDATE query will look like this:


              1234567
            
UPDATE medications
SET price = 4
WHERE id = 2;

SELECT * 
FROM medications
ORDER BY id;

Here, we updated the medications table so that the price for the product with id 2 (ibuprofen) will be set to 4. After that, we selected all the columns from the table to ensure the price column was successfully updated. You can substitute any value and see how the update operation works in SQL:

sql

The syntax for deletion will look like this:

sql

But I'll remind you that deleting rows should be done with caution, as you won't be able to simply recover them.

Note

If you don't include a WHERE condition, the data will be updated or deleted for all rows.

Compito

Swipe to start coding

In the pharmaceutical market, there's inflation!

The supplier company informed us that we must urgently establish a minimum price of 10 units for the product. So your task will be to update the table so that the price, which was previously less than 10, becomes 10. You can do this using the UPDATE statement.

Brief Instructions

Use the UPDATE statement to modify the medications table.
Use SET to assign a new value of 10 to the price column.
Use the WHERE clause with the condition price < 10 so that the update only applies to rows meeting this requirement.

Soluzione

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Sezione 4. Capitolo 4

UPDATE and DELETE

It's time to get back to writing queries and consider two more statements.

You already know how to clear a table, add a column, insert data, etc. But for proper interaction with the database, we need to understand how to update and delete individual rows.

For this, there are two statements and types of queries: the UPDATE and the DELETE queries.

Let's look at an example with the medications table:

Let's imagine we need to update the price for a specific type of medication. For example, currently, there's a 50% discount on ibuprofen, and we need to change the price for this product.

Our UPDATE query will look like this:


              1234567
            
UPDATE medications
SET price = 4
WHERE id = 2;

SELECT * 
FROM medications
ORDER BY id;

sql

The syntax for deletion will look like this:

sql

But I'll remind you that deleting rows should be done with caution, as you won't be able to simply recover them.

Note

If you don't include a WHERE condition, the data will be updated or deleted for all rows.

Compito

Swipe to start coding

In the pharmaceutical market, there's inflation!

Brief Instructions

Use the UPDATE statement to modify the medications table.
Use SET to assign a new value of 10 to the price column.
Use the WHERE clause with the condition price < 10 so that the update only applies to rows meeting this requirement.

Soluzione

Cambia al desktop per esercitarti nel mondo realeContinua da dove ti trovi utilizzando una delle opzioni seguenti

Tutto è chiaro?

Grazie per i tuoi commenti!

Sezione 4. Capitolo 4

Cambia al desktop per esercitarti nel mondo realeContinua da dove ti trovi utilizzando una delle opzioni seguenti