How to create an AND button that adds a AND statement to a query?

问题

I'm making some type of query builder and I want to implement a button to add a AND statement to my query. I made a version where I have 1 AND statement implemented but it's a bit devious and I want the user to have the ability to do more than one AND statement. This the code I have at the moment.

UPDATEDThis is my .php file:

   <?php

include "connect.php";

//Ophalen van de waarden uit de tabel(len) en veld(en) 
$table          = $_GET['tableSelected'];
$field          = $_GET['fieldSelected'];
$attribute      = $_GET['attributeSelected'];
$operator       = $_GET['operatorSelected'];
$fieldList      = $_GET['fieldList'];

$fieldstr = $fieldList . ",ST_AsGeoJSON(ST_Transform(l.geom,4326))";

$sql = "SELECT $fieldstr
        FROM $table l";

if (!empty($field) && !empty($operator) && !empty($attribute)) {
    $sql .= " WHERE {$field} {$operator} '{$attribute}' AND {$field}";
};

//echo ($sql);
?>

And here is a image of what it should look like:

回答1:

A few things:

Your current sql will fail if the first pair is emptied as there will be no WHERE but only AND clauses.
Using arrays in html allows you to use arrays in php, making everything a lot easier to process by looping over it.

A simple example:

html:

<select name="field[]">...</select>
<select name="operator[]">...</select>
<select name="value[]">...</select>

You can use javascript to add more pairs of the exact same code.

Now in php your $_POST variables will be arrays so you can do something like:

$sql = 'SELECT ...';

# this array will contain all "AND" conditions
$pairs = [];

# loop over all your select groups
foreach ($_POST['field'] as $key => $field) {
    if (!empty($field) && !empty($_POST['operator'][$key]) && !empty($_POST['value'][$key])) {
        $pairs[] = $field . " " . $_POST['operator'][$key] . " '" . $_POST['value'][$key] . "'";
    }
}

# add the conditions
if (count($pairs) > 0) {
    $sql .= ' WHERE ' . implode(' AND ', $pairs);
}

# add sort order, execute sql, etc...

By the way, you should replace the value with a placeholder and use white-lists for the database-, table and column names and the operators to avoid sql injection / breaking your query.

来源：https://stackoverflow.com/questions/37807123/how-to-create-an-and-button-that-adds-a-and-statement-to-a-query

标签

javascript

sql

button

query-builder