Grouping the same rows for a column in PHP/MySQL

Question

Assume that I have a table structure like seen below

location|name 
------------- 
NY|john  
London|neil  
NY|clair

I retrieve data using

SELECT * FROM table

The HTML view file is as follows:

<table>  
<tr><td>location</td><td>name</td>  
<?php foreach($rows as $row):>  
<tr><td><?=$row->location></td><td><?=$row->name></td>  
<?php endforeach;>  
</table>

As you can guess, it outputs every column for a row multiple times.

What I actually want is, to list them as,

NY
            john
            clair

London
            neil

It would also be great if I can use alternating colors between NY and London.

ps: I have too many things to group, simple workarounds will not fit.

Answer 1

For your example, I would do:

SELECT * FROM table ORDER BY location

Now, the locations will be in groups. You can add more of these columns comma-separated.

Next, for the PHP:

<?php $lastLocation = 'havenotseenityet'; ?>
<table>  
<tr><td>location</td><td>name</td>  
<?php foreach($rows as $row):>  
    <tr>
    <?php if ($lastLocation != $row->location) {
        $lastLocation = $row->location;
        ?>
    <td><?=$row->location></td><td><?=$row->name></td>
    <?php
    } else {
        ?>
        <td></td><td><?=$row->name></td>  
    } ?>
<?php endforeach;>  
</table>

What we're doing here is getting the rows so that the locations that are the same are next to each other (and sorted -- being next to each other is a side effect). Then we're tracking the last location we saw, and when we see a new one, we show the location, and otherwise we hide it till we see a new one. This can be extended to any number of items, though remember that if you sort by state, city , then when you see a different state, you have to make city not seen too.

Finally, note that I didn't start with $lastLocation = null. That is because null is a valid value for DB columns, and you don't want to trip up on that.

Answer 2

在查询中尝试使用DISTINCT location

Answer 3

If you want to use a table with alternating colors for the table rows, I suggest that you use the frontend framework Bootstrap. Read more about this here .

For another similar issue with alternating row colors ("striped rows"), with a solution using Bootstrap, please see Alternating Row Colors in Bootstrap 3 - No Table

Note: The first link relates to Bootsrap v.4, and the second relates to Bootstrap v.3. Both should give you an understanding of the striped rows feature, independent of Bootstrap version.