How to query database content in php

How to query database content in php: 1. Execute select query through "mysqli_query()" method; 2. Query through "PDO::__query()" method.

The operating environment of this article: windows7 system, PHP7.1 version, DELL G3 computer

How to query the database content with php?

PHP MySQL Select query data

PHP mysql_query() function is used to execute select queries. Since PHP 5.5, the mysql_query() function is deprecated. Now, it is recommended to use one of the following 2 alternatives.

mysqli_query()
PDO::__query()

There are two other MySQLi functions in the select query.

mysqli_num_rows(mysqli_result $result): Returns the number of rows. mysqli_fetch_assoc(mysqli_result $result): Returns an associative array of rows. Each key name of the array is a column name of the table. If there is no row data, NULL is returned.

PHP MySQLi select query example

<?php  
$host = &#39;localhost:3306&#39;;  
$user = &#39;root&#39;;// 
$pass = &#39;&#39;;  
$dbname = &#39;test&#39;;  
$conn = mysqli_connect($host, $user, $pass,$dbname);  
if(!$conn){  
  die(&#39;Could not connect: &#39;.mysqli_connect_error());  
}  
echo &#39;Connected successfully<br/>&#39;;  
$sql = &#39;SELECT * FROM emp4&#39;;  
$retval=mysqli_query($conn, $sql);  
if(mysqli_num_rows($retval) > 0){  
 while($row = mysqli_fetch_assoc($retval)){  
    echo "EMP ID :{$row[&#39;id&#39;]}  <br> ".  
         "EMP NAME : {$row[&#39;name&#39;]} <br> ".  
         "EMP SALARY : {$row[&#39;salary&#39;]} <br> ".  
         "--------------------------------<br>";  
 } //end of while  
}else{  
echo "0 results";  
}  
mysqli_close($conn);  
?>

PHP

Execute the above code to get the following results-

Tip: There must be relevant data in the emp4 table

Connected successfully
EMP ID :1 
EMP NAME : maxsu 
EMP SALARY : 9000 
--------------------------------
EMP ID :2 
EMP NAME : minsu 
EMP SALARY : 40000 
--------------------------------
EMP ID :3 
EMP NAME : jaizhang
EMP SALARY : 90000 
--------------------------------

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