Deleting Data in MySQL
By: Sathya Narayana in MySQL Tutorials on 2010-10-24
To delete a given row or set of rows, you use the DELETE FROM...WHERE command. For instance, you can delete the book called Mr Bunny's Guide to JDO with this command:
mysql> DELETE FROM book -> WHERE title = "Mr Bunny's Guide to JDO";
Now execute a SELECT command to retrieve all books from the table, and you'll see that the record for that book no longer appears:
+----+-------------------------------------------+-------+ | id | title | price | +----+-------------------------------------------+-------+ | 1 | Lord of the Things | 8.99 | | 3 | Parachuting for You and Your Kangaroo | 19.99 | +----+-------------------------------------------+-------+
Be careful when using DELETE because once a row is removed, it's lost forever. Hence, be particularly wary when specifying a nonunique column in the WHERE clause, such as you have here. In your small database, you know that only a single row will be deleted, but in a real-world database, you can easily end up accidentally deleting a whole bunch of records if you use a badly thought-out WHERE clause. You can reduce the chances of this happening by specifying a WHERE clause on a uniquely valued field (such as a primary key).
We've now covered enough of the basics of the SQL syntax to move on and show how you can use it to access databases in a JSP page.
This policy contains information about your privacy. By posting, you are declaring that you understand this policy:
- Your name, rating, website address, town, country, state and comment will be publicly displayed if entered.
- Aside from the data entered into these form fields, other stored data about your comment will include:
- Your IP address (not displayed)
- The time/date of your submission (displayed)
- Your email address will not be shared. It is collected for only two reasons:
- Administrative purposes, should a need to contact you arise.
- To inform you of new comments, should you subscribe to receive notifications.
- A cookie may be set on your computer. This is used to remember your inputs. It will expire by itself.
This policy is subject to change at any time and without notice.
These terms and conditions contain rules about posting comments. By submitting a comment, you are declaring that you agree with these rules:
- Although the administrator will attempt to moderate comments, it is impossible for every comment to have been moderated at any given time.
- You acknowledge that all comments express the views and opinions of the original author and not those of the administrator.
- You agree not to post any material which is knowingly false, obscene, hateful, threatening, harassing or invasive of a person's privacy.
- The administrator has the right to edit, move or remove any comment for any reason and without notice.
Failure to comply with these rules may result in being banned from submitting further comments.
These terms and conditions are subject to change at any time and without notice.
- Data Science
- React Native
- Cloud Computing
- Java Beans
- Mac OS X
- Office 365
- Tech Reviews
Use a dynamic table name in a SQL Server SELECT statement
Finding slow queries in MySQL - Enable slow query log.
mysqldumpslow in MySQL - Summarize slow query log.
Sample my.cnf (my.ini) for MySQL with 1GB RAM
Modify a auto_increment id column in mysql to accept a 5 digit random number instead
Windows cannot access the specified device, path or file. You may not have the appropriate permissions to access them.
ERROR 1251: Client does not support authentication protocol requested by server; consider upgrading MySQL client
Changing the Structure of an Existing Table in MySQL
Inserting Data into Tables in MySQL
Querying the Database in MySQL
Modifying data and using WHERE clause in MySQL