参考已加入MySQL数据（如JSON表）

Question

The title may be weird, as I'm not sure how to word what I'm doing.

I am building a roster system that will be sorted by designations (think Division, Company, Platoon, etc.). I want this display to be completely dynamic, and I am trying to be as slick as possible in doing it.

In the same database I have 2 tables that are not equal, though they share a couple column names where sometimes the data values are equal, sometimes they aren't. The table tali_personnel_designations_weights stores the categories of designation (Division, Company, etc.) while table tali_personnel_designations stores the actual designations (3rd Infantry Division, Kilo Company, etc.). There are a bunch of things going on, but the answer to 1 will get me back on the road. Both tables have a column named 'name' which contains, well, the name of that entry, such as Division for the _weights and 3rd Infantry Division for the designation. In my SQL I want to be able to select both names, but as it is below the only return is from tali_personnel_designations_weights, as if the first table was re-written in the result.

$SQL = "SELECT * FROM tali_personnel_designations JOIN tali_personnel_designations_weights ON tali_personnel_designations.designation_weight_id=tali_personnel_designations_weights.designation_weight_id ORDER BY tali_personnel_designations_weights.weight DESC, tali_personnel_designations.weight DESC";
$result = mysqli_query($db_handle, $SQL);

while ($db_field = mysqli_fetch_assoc($result)) {
    $name = $db_field['name'];
    echo $name; //output is value for 'name' in tali_personnel_designations_weights
    echo "<br/>";
}

What I'm trying to do, if you can visualize it:

$designation_name = $db_field['tali_personnel_designations.name']; //output 3rd Infantry Division
$designationweight_name = $db_field['tali_personnel_designations_weights.name']; //output Division

I understand the easy fix for this is renaming the columns so that 'name' does not conflict, but I'm trying to learn something new here!

Thanks for the help.

Answer 1

Your query should be something like this:

SELECT
    T.*, 
    T.name AS designation_name,
    TW.name AS designation_weight_name
FROM tali_personnel_designations T
JOIN tali_personnel_designations_weights TW
    ON T.designation_weight_id=TW.designation_weight_id
ORDER BY TW.weight DESC, T.weight DESC

Then when using the result you can get the $db_field['designation_name'] and $db_field['designation_weight_name'] , and don't mind of the (also present) $db_field['name'] .

Note that using alias for the table names makes it much more readable.