Mysql updating a table from another table
You can add, remove, edit, backup and view your databases using this and it is especially useful when troubleshooting your databases.Throughout this tutorial I will be showing you some of the basics of using PHP and My SQL together.Freedom2Surf are a free (banner supported) web host and support PHP and have My SQL installed.Host Rocket are an excellent web host and can offer you 300MB of space with PHP, My SQL and loads of other extras for under a month.Some examples of PHP and My SQL being used together are: You only really need three things to run PHP scripts which access My SQL databases. This can either be on a computer of your own or on a web host. You can also use most other types of database (SQL, Oracle etc.) but as this is a PHP/My SQL tutorial I will deal just now with the My SQL database (although the commands used here will also work with SQL databases).Any web server software should work with PHP and My SQL but the best to use is Apache, which is free. If it is not already installed you can install it (or ask your web host to install it). If you are not sure if you have PHP installed I will show you a way to check it later. As with the other software you need, My SQL is free and can be downloaded from the My SQL homepage.My Sql sessions have the safe-updates option set by default.This means that you can't update or delete records without specifying a key (e.g. Attempting to update records without specifying a key will result in an error: Error Code: 1175.
If you cannot install (or your web host won't allow) PHP and My SQL you can still use another web host.
Say that we added another field to the high_priced_rentals table to track restricted (i.e.
18 ) movies: A WHERE clause can be added to further limit updated rows.
Forget the fact that it goes against 3NF (normalization) conventions. The ID will always be unique, but the other fields may or may not be. Updating records with data from another table is not quite so simple because there is no UPDATE…SELECT statement.
Instead, updates use table joins to connect related rows to each other.
You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column.