Getting
to Grips with mySQL - Page 4
      by Granville Barnett aka G  |  13 July 2005

Step 7
Now we are going to update a record, here is where our id column comes in very handy!! In the mySQL terminal type in the command to view the records so that all columns appear then find a user to which you want to modify their details – look at their corresponding id number!! then type in the following command:

UPDATE users SET
name=”Kirupa.com”,
location=”Spain”,
date=CURDATE()
WHERE id=4;

You should see:

See how I update record with id 4 (WHERE id=4) I changed the name of the user and location of the user to Kirupa.com and Spain respectively.

Hopefully by now the power of SQL is sinking in, and I've barely touched the surface!! Now let me explain one last key function that you will no doubt need – the DELETE statement.

Step 8
Once again display the contents of the users' table and find someone you want to delete then make a note of their corresponding id number. Type in the following:

DELETE FROM users WHERE id=4;

In the above statement I deleted this row:

Sorry Kirupa. Now lets view the contents of our table again and see if anything has changed.

See how the kirupa record has gone?? well I hope you do!!

Note
Use the DELETE statement with great care as unlike some applications etc (mySQL is not really an application but rather a database server) you cannot retrieve a previously deleted record. It is possible to make incremental backups of your database and restore data that way – again this is out of the scope of this tutorial.

 
Conclusion

What we have just done is covered the following:

  • Creating a database
  • Creating a table and specifying the tables column names and their acceptable values.
  • Inserting data into our table
  • Selecting our data in a specific way that we see only the information we asked for and in a specific order
  • Updating a record in our table
  • Deleting a record in our table

Hopefully by now you will know these statements well! Don't forget that in languages such as PHP you can quote the exact same query statements covered in this tutorial.

If you have any questions, please contact me or post on the forums.

G
www.apixelmind.com


 


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