PHP mysqli_warning_count()用法及代码示例

定义和用法

如果您的最后一个 MySQLi 函数调用执行 MySQL 查询并且它生成任何错误。这mysqli_warning_count()函数计算上次执行的查询产生的错误数，并返回结果。

用法

mysqli_warning_count($con)

参数

Sr.No	参数及说明
1	con(Mandatory) 这是一个表示与 MySQL 服务器的连接的对象。

返回值

PHP mysqli_warning_count() 函数返回一个整数值，表示在执行上次查询期间生成的警告数。如果上次执行期间没有警告，则此函数返回 0

PHP版本

这个函数最初是在 PHP 版本 5 中引入的，适用于所有后续版本。

假设我们创建了一个名为 Emp 的表，如下所示 -

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

示例

以下示例演示了 mysqli_warning_count() 函数的用法(程序风格) -

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

   //Inserting a record into the employee table
   $sql = "INSERT IGNORE into emp values(1, 'Sanjay', NULL, DATE('1981-12-05'), 2566)";
   mysqli_query($con, $sql);
   //Number of Warnings
   $count = mysqli_warning_count($con);
   print("Number of Warnings:".$count ."\n");

   $sql = "INSERT IGNORE into emp values (15, 'Swetha', 'Yellapragada', DATE('1990-11-25'), 9986), (15, NULL, 'Prayaga', DATE('1990-11-25'), 9986)";
   mysqli_query($con, $sql);
   //Number of Warnings
   $count = mysqli_warning_count($con);
   print("Number of Warnings:".$count);

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

这将产生以下结果 -

Number of Warnings:1
Number of Warnings:2

示例

在面向对象的风格中，这个函数的语法是 $con -> warning_count，其中，$con 是连接对象 -

<?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, 'Sanjay', NULL, DATE('1981-12-05'), 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, 'Swetha', 'Yellapragada', DATE('1990-11-25'), 9986), (15, NULL, 'Prayaga', DATE('1990-11-25'), 9986)");
   //Number of Warnings
   $count2 = $con->warning_count;
   print("Number of Warnings:".$count2);

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

这将产生以下结果 -

Number of Warnings:0
Number of Warnings:2

示例

以下是函数 mysqli_warning_count() 的另一个示例 -

<?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($con, "INSERT IGNORE into emp values(107, 'Sunitha', NULL, DATE('1981-12-05'), 2566)");
   mysqli_query($con, "INSERT IGNORE into emp values(7, 'Mohit', 'Sharma', DATE('1981-12-05'), 2566)");
   print("No.Of Warnings (if before last query contains errors):".mysqli_warning_count($con)."\n");

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

这将产生以下结果 -

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

示例

<?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,'Rajesh Ramayan Kootrapally')";

   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);
?>

这将产生以下结果 -

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