Removing data
SQL commands also allow for the deletion of a record in the database. This syntax is exactly the same as the UPDATE or
SELECT statement except using the DELETE keyword.
For the this tutorial, the following table will be used again:
| Product_ID | type | quantity |
|---|---|---|
| 32 | Apple | 10 |
| 45 | Orange | 91 |
| 78 | Apricots | 25 |
| 141 | Pear | 34 |
It's very important that the WHERE clause is used in conjunction with the DELETE
statement to restrict what data is removed. Following the same pattern as shown in the WHERE clause example with
fruits, the following statement will remove all apples and pears which have a quantity less than 9.
SQL
DELETE FROM `fruits` WHERE (type="Apple" OR type="Pear") AND quantity < 9
Clearing a table
Sometimes it is necessary to clear an entire table. This can be done using a syntax similar to the SELECT * syntax:
SQL
DELETE * FROM `fruits`
However, SQL also permits the omission of the * here:
SQL
DELETE FROM `fruits`
Did you know my courses are all printer-friendly? This means you can easily export them to PDF or print them for later use.
