Tutorials - MySQL - Queries - Where

Now that you have seen how you can store and retrieve data in MySQL databases, you might be wondering how you can get back specific data. Luckily, you don't have to use PHP to filter through your data (especially since you might end up with database tables which have millions of rows), but you can use the WHERE clause in your SQL statement to control which data is returned

First, we'll add some more data to our customers table so that we can demonstrate this. We are going to leave out the PHP sections of the code from now on, unless we introduce something new, so that you can see what is happening with the SQL

INSERT INTO `customers`(`taxid`, `name`, `address`) VALUES (`789012`, `Daniel Davidson`, `45 Made Up Road`)
INSERT INTO `customers`(`taxid`, `name`, `address`) VALUES (`654321`, `Tom Thompson`, `1 Not Real Close`)
INSERT INTO `customers`(`taxid`, `name`, `address`) VALUES (`135792`, `Eddie Ericson`, `975C Imaginary Drive`)

Now we can use SELECT with WHERE to get specific sets of data from our table. For example, if we have the taxid "654321" and we want to know who it belongs to, we could use the MySQL query:

SELECT `name` FROM `customers` WHERE `taxid` = '654321'

Tom Thompson

You can also use '>' and '<' to compare numerical columns:

SELECT `address` FROM `customers` WHERE `customerid` < 3

123 Fake Street 45 Made Up Road

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