PHP | mysqli_warning_count() Function

Hello folks! welcome back to a new edition of our tutorial on PHP. In this tutorial guide, we are going to be studying about the PHP mysqli_warning_count() Function.

The built-in PHP mysqli_warning_count() function counts the number of errors that was generated by the last executed query and, returns the result.

Syntax

Following below is the syntax to use this function -

mysqli_warning_count($con)

READ: PHP | mysqli_set_charset() Function

Parameter Details

Sr.No	Parameter & Description
1	con(Mandatory) This is an object representing a connection to MySQL Server.

Return Value

This built-in PHP function returns an integer value representing the number of warnings generated during the execution of the last query. If there are no warnings during the last execution, this built-in function returns 0.

PHP Version

This PHP function was first introduced in PHP version 5 and works in all the later versions.

Example1

Assuming we have created a table named Emp as follows -

CREATE TABLE EMP(
    ID TINYINT,
    First_Name VARCHAR(50) Not NULL, 
    Last_Name VARCHAR(10) Not NULL, 
    Date_Of_Birth date, 
    Salary Int(255)
);

The following below is an example which demonstrates the usage of the built-in PHP mysqli_warning_count() function (in a procedural style) -

<?php
   //Creating a connection
   $con = mysqli_connect("localhost", "root", "password", "mydb");

   //Inserting a record into the employee table
   $sql = "INSERT IGNORE into emp values(1, 'Kennedy', NULL, DATE('1993-04-05'), 2566)";
   mysqli_query($con, $sql);
   //Number of Warnings
   $count = mysqli_warning_count($con);
   print("Number of Warnings: ".$count ."\n");

   $sql = "INSERT IGNORE into emp values (15, 'Precious', 'Amah', DATE('1995-02-22'), 9986), (15, NULL, 'Paul', DATE('1990-11-25'), 9986)";
   mysqli_query($con, $sql);
   //Number of Warnings
   $count = mysqli_warning_count($con);
   print("Number of Warnings: ".$count);

   //Closing the connection
   mysqli_close($con);
?>

Output

When the above code is executed, it will produce the following result -

Number of Warnings: 1
Number of Warnings: 2

Example2

In an object oriented style the syntax of this function is $con->warning_count; Following is the example of this function in an object oriented style -

<?php
   //Creating a connection
   $con = new mysqli("localhost", "root", "password", "mydb");

   //Inserting a record into the employee table
   $con -> query("INSERT IGNORE into emp values(1, 'Kennedy', NULL, DATE('1993-04-05'), 2566)");
   //Number of Warnings
   $count1 = $con->warning_count;
   print("Number of Warnings: ".$count1."\n");

   //Inserting a record into the employee table
   $con -> query("INSERT IGNORE into emp values(15, 'Precious', 'Amah', DATE('1995-02-22'), 9986), (15, NULL, 'Paul', DATE('1990-11-25'), 9986)");
   //Number of Warnings
   $count2 = $con->warning_count;
   print("Number of Warnings: ".$count2);

   //Closing the connection
   $con -> close();
?>

Output

When the above code is executed, it will produce the following result -

Number of Warnings: 0
Number of Warnings: 2

Example3

Following is another example of the PHP mysqli_warning_count() function.

<?php
   //Creating a connection
   $con = mysqli_connect("localhost", "root", "password", "mydb");

   //Warning count for proper query
   mysqli_query($con, "SELECT * FROM EMP");
   print("No.Of Warnings (proper query): ".mysqli_warning_count($con)."\n");

   //Query to DROP an unknown table
   mysqli_query($con, "drop table if exists WrongTable");
   print("No.Of Warnings: ".mysqli_warning_count($con)."\n");

   //Warnings of before last statement
   mysqli_query($con, "INSERT IGNORE into emp values(107, 'Justice', NULL, DATE('1992-12-05'), 2566)");
   mysqli_query($con, "INSERT IGNORE into emp values(7, 'Stephanie', 'Francis', DATE('1997-12-05'), 2566)");
   print("No.Of Warnings (if before last query contains errors): ".mysqli_warning_count($con)."\n");

   //Closing the connection
   mysqli_close($con);
?>

Output

When the above code is executed, it will produce the following result -

Insert ID (select query): 0
Insert ID: (multiple inserts) 6
Insert ID (update query): 0
Insert ID: (table with out auto incremented key) 0

Example4

Try the following example below -

<?php
   $servername = "localhost";
   $username = "root";
   $password = "password";
   $dbname = "mydb";
   $conn = new mysqli($servername, $username, $password, $dbname);

   if (!$conn->real_connect($servername, $username, $password, $dbname)) {
      die('Connect Error (' . mysqli_connect_errno() . ') '. mysqli_connect_error());
   }
   print("Database connected" ."\n");
   mysqli_query($conn, "CREATE TABLE sample (ID INT, Name VARCHAR(20))");
   $query = "INSERT IGNORE INTO sample (id,name) VALUES(
      1,'Nkpara Kennedy Chinaza')";

   mysqli_query($conn, $query);
   $warnings = mysqli_warning_count($conn);
   print("No.Of warnings in the query:".$warnings."\n");

   if ($warnings) {
      if ($result = mysqli_query($conn, "SHOW WARNINGS")) {
         $row = mysqli_fetch_row($result);
         printf("%s (%d): %s\n", $row[0], $row[1], $row[2]);
         mysqli_free_result($result);
      }
   }

   mysqli_close($conn);
?>

Output

When the above code is executed, it will produce the following result -

Database connected
No.Of warnings in the query:1
Warning (1265): Data truncated for column 'Name' at row 1

READ: PHP | mysqli_stmt_init() Function

Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we are going to be discussing about the mysqli_data_seek() Function in PHP.

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