Archie  Clayton

Archie Clayton

1551239161

PHP Query a table column based on value from another column in same table

I have a database I have to query using PHP. There are 3 different columns I'm dealing with. What I have to do require a handful of steps so I'll list the steps 1 by 1...... 1) I have to go through each value in the 'nid' column. However, some of the 'nids' have duplicate value. Therefore I have to choose the 'nid' with the highest 'vid' value. 2) Once I select the 'nid' with the highest 'vid' value I then have to get the value of the 'title' column that's in the same row of the highest 'vid'. For example if I have a 'vid' of 1253 I have to select the content that's in column title that corresponds with 'vid' 1253. I have a lot of the steps. However, I'm getting stuck on once I grab the highest vid, being able to grab the content in the title column. Below is my code

<?php
    // Establish all database credential variables
    $serverName = "localhost";
    $username = "root";
    $password = "root";
    $databaseName = "redesign_static";
    // Create Database Connection
    $connection = new mysqli($serverName, $username, $password, $databaseName);
    // Check Database Connection
    if ($connection->connect_error) {
      die("Connection failed:" . $connection->connect_error);
    } // line ends if statement
    $queryNodeRevision = "SELECT nid, vid, title FROM node_revision";
    // line above creates variable $queryNodeRevision > selects column "nid" from table "node_revision"
    $results = mysqli_query($connection, $queryNodeRevision) or die("Bad Query: $results");
    // line above creates variable $results > actually queries that database and passes in variable "$queryNodeRevision"
    $storeNIDAndVIDValues = []; // empty array to store max 'vid' values
for ($i = 0; $i &lt; 8000; $i++) {
  $storeNIDAndVIDValues[$i] = 0;
  // line above assigns initial 'vid'; starts at 0
}

while ($row = mysqli_fetch_array($results)) {
  $currentNID = $row['nid'];
  // line above creates variable that represents the current 'nid' of row (aka the key)
  $currentVID = $row['vid'];
  // line above creates variable that represents the current value of the 'vid' (the number you want to compare)
if ($currentVID &gt; $storeNIDAndVIDValues[$currentNID]) {
    // if the value of'$currentVID' is greater than what's stored in array '$storeNIDAndVIDValues' at current nid position
    // $storeNIDAndVIDValues[$currentNID] = goes into array $storeNIDAndVIDValues and gets the value of nid key (in this case value represents what position the nid is at)
       $storeNIDAndVIDValues[$currentNID] = $currentVID;
       // line above &gt; becomes max 'vid' at that time 
       $titleOfSelectedVID = $row['title'];
      // $row['title'] = gets the value of the current 'title'
    $queryTitle = "SELECT title FROM node_revision WHERE $currentVID ";
    // line above is query variable that targets 'title' column row that has highest 'vid' value
 } // line ends if statement
} // line closes while loop

?>

$queryTitle = "SELECT title FROM node_revision WHERE

The $queryTitle line is where I’m getting stuck. This is where I want to get the content of title column but only the title that corresponds with the highest vid.

#php #mysql #sql #database

What is GEEK

Buddha Community

Garry Taylor

1551242013

Try write query as below

SELECT nid,MAX(vid) as vid,title FROM node_revision GROUP BY nid

Archie  Clayton

Archie Clayton

1551239161

PHP Query a table column based on value from another column in same table

I have a database I have to query using PHP. There are 3 different columns I'm dealing with. What I have to do require a handful of steps so I'll list the steps 1 by 1...... 1) I have to go through each value in the 'nid' column. However, some of the 'nids' have duplicate value. Therefore I have to choose the 'nid' with the highest 'vid' value. 2) Once I select the 'nid' with the highest 'vid' value I then have to get the value of the 'title' column that's in the same row of the highest 'vid'. For example if I have a 'vid' of 1253 I have to select the content that's in column title that corresponds with 'vid' 1253. I have a lot of the steps. However, I'm getting stuck on once I grab the highest vid, being able to grab the content in the title column. Below is my code

<?php
    // Establish all database credential variables
    $serverName = "localhost";
    $username = "root";
    $password = "root";
    $databaseName = "redesign_static";
    // Create Database Connection
    $connection = new mysqli($serverName, $username, $password, $databaseName);
    // Check Database Connection
    if ($connection->connect_error) {
      die("Connection failed:" . $connection->connect_error);
    } // line ends if statement
    $queryNodeRevision = "SELECT nid, vid, title FROM node_revision";
    // line above creates variable $queryNodeRevision > selects column "nid" from table "node_revision"
    $results = mysqli_query($connection, $queryNodeRevision) or die("Bad Query: $results");
    // line above creates variable $results > actually queries that database and passes in variable "$queryNodeRevision"
    $storeNIDAndVIDValues = []; // empty array to store max 'vid' values
for ($i = 0; $i &lt; 8000; $i++) {
  $storeNIDAndVIDValues[$i] = 0;
  // line above assigns initial 'vid'; starts at 0
}

while ($row = mysqli_fetch_array($results)) {
  $currentNID = $row['nid'];
  // line above creates variable that represents the current 'nid' of row (aka the key)
  $currentVID = $row['vid'];
  // line above creates variable that represents the current value of the 'vid' (the number you want to compare)
if ($currentVID &gt; $storeNIDAndVIDValues[$currentNID]) {
    // if the value of'$currentVID' is greater than what's stored in array '$storeNIDAndVIDValues' at current nid position
    // $storeNIDAndVIDValues[$currentNID] = goes into array $storeNIDAndVIDValues and gets the value of nid key (in this case value represents what position the nid is at)
       $storeNIDAndVIDValues[$currentNID] = $currentVID;
       // line above &gt; becomes max 'vid' at that time 
       $titleOfSelectedVID = $row['title'];
      // $row['title'] = gets the value of the current 'title'
    $queryTitle = "SELECT title FROM node_revision WHERE $currentVID ";
    // line above is query variable that targets 'title' column row that has highest 'vid' value
 } // line ends if statement
} // line closes while loop

?>

$queryTitle = "SELECT title FROM node_revision WHERE

The $queryTitle line is where I’m getting stuck. This is where I want to get the content of title column but only the title that corresponds with the highest vid.

#php #mysql #sql #database

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Ahebwe  Oscar

Ahebwe Oscar

1620185280

How model queries work in Django

How model queries work in Django

Welcome to my blog, hey everyone in this article we are going to be working with queries in Django so for any web app that you build your going to want to write a query so you can retrieve information from your database so in this article I’ll be showing you all the different ways that you can write queries and it should cover about 90% of the cases that you’ll have when you’re writing your code the other 10% depend on your specific use case you may have to get more complicated but for the most part what I cover in this article should be able to help you so let’s start with the model that I have I’ve already created it.

**Read More : **How to make Chatbot in Python.

Read More : Django Admin Full Customization step by step

let’s just get into this diagram that I made so in here:

django queries aboutDescribe each parameter in Django querset

we’re making a simple query for the myModel table so we want to pull out all the information in the database so we have this variable which is gonna hold a return value and we have our myModel models so this is simply the myModel model name so whatever you named your model just make sure you specify that and we’re gonna access the objects attribute once we get that object’s attribute we can simply use the all method and this will return all the information in the database so we’re gonna start with all and then we will go into getting single items filtering that data and go to our command prompt.

Here and we’ll actually start making our queries from here to do this let’s just go ahead and run** Python manage.py shell** and I am in my project file so make sure you’re in there when you start and what this does is it gives us an interactive shell to actually start working with our data so this is a lot like the Python shell but because we did manage.py it allows us to do things a Django way and actually query our database now open up the command prompt and let’s go ahead and start making our first queries.

#django #django model queries #django orm #django queries #django query #model django query #model query #query with django

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