Detailed explanation of PHP7 database connection and addition, deletion, query and modification (mysqli method)-PHP7-php.cn

Detailed explanation of PHP7 database connection and addition, deletion, query and modification (mysqli method)

藏色散人

Release： 2023-02-17 18:00:02

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## Use the mysqli method to achieve the following functions (php7):

1. Connect to the MySQL database server;

2. Create a database named test;
3. Create a data table named "testTable" in the database. The data table contains at least three fields. Field names, types and attributes are customized;
4. Insert three records into the database and query all data in the data table;
5. Modify one of the records and query all data in the data table;
6. Delete one of the records and query all the data in the data table;





mysqli方法实现连接数据库，及增删查改



";
	}
	else{
		echo "数据库连接失败！
";
	}


	$sql="CREATE DATABASE test";
	if (mysqli_query($con,$sql)){
	echo "数据库创建成功!
";
	}else{
	echo "数据库创建失败!
".mysqli_error($con)."
";
	}
	

	mysqli_select_db($con,"test");
	$table="CREATE TABLE testTable(
	student_id int(11) auto_increment primary key,
	student_no char(10) not null unique,
	student_name char(20) not null)";
	if(mysqli_query($con,$table)){
		echo "数据表创建成功!
";
	}
	else{
		echo "数据表创建失败!
".mysqli_error($con)."
";
	}
	
	$mysqli=new mysqli("localhost","root","15118595615","test");
	$query="select * from testTable";
	$insertdatas=mysqli_query($con,"insert into testTable(student_id,student_no,student_name) values('null','20170001','张三')");
	mysqli_free_result($insertdatas);
	$insertdatas=mysqli_query($con,"insert into testTable(student_id,student_no,student_name) values('null','20170002','李四')");
	mysqli_free_result($insertdatas);
	$insertdatas=mysqli_query($con,"insert into testTable(student_id,student_no,student_name) values('null','20170003','王五')");
	if($insertdatas){
		echo "数据插入成功！
";
		$result=$mysqli->query($query);
		foreach($result as $row){
			echo $row["student_id"].'  ';
			echo $row["student_no"].'  ';
			echo $row["student_name"]."
";
		}
	}
	else{
		echo "数据插入失败！
".mysqli_error($con)."
";
	}
	mysqli_free_result($insertdatas);


	$up=mysqli_query($con,"update testTable set student_no='20180001' where student_name='张三'");
	if($up){
		echo "数据更新成功!
";
		$result=$mysqli->query($query);
		foreach($result as $row){
			echo $row["student_id"].'  ';
			echo $row["student_no"].'  ';
			echo $row["student_name"]."
";
		}
	}
	else{
		echo "数据更新失败!
".mysqli_error($con)."
";
	}
	mysqli_free_result($up);


	$del=mysqli_query($con,"delete from testTable where student_name='李四'");
	if($del){
		echo "数据删除成功!
";
		$result=$mysqli->query($query);
		foreach($result as $row){
			echo $row["student_id"].'  ';
			echo $row["student_no"].'  ';
			echo $row["student_name"]."
";
		}
	}
	else{
		echo "数据删除失败!
".mysqli_error($con)."
";
	}
	mysqli_free_result($del);
	
	mysqli_close($con);
    
?>

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The final effect is as follows:

Detailed explanation of PHP7 database connection and addition, deletion, query and modification (mysqli method) When writing code Pay attention to some differences between PHP7 and PHP5:
1. PHP7 needs to replace PHP5’s
mysql() with mysqli(); 2. PHP7’s query statement must Written as
mysqli( $ c o n n e c t , , Connect, c o n n e c t, sql)$ , the writing method of PHP5 is opposite to that of PHP7mysql( $ s q q l , sql, s q l, connect）$ ；

Warm reminder: Be sure to use the mysqli_free_result() function to release resources after each query! Otherwise, an error will be reported and the next query statement cannot be executed! I took a lot of detours when I was a beginner, and I have learned hard lessons. I hope it can help my beginner friends to avoid detours!

用mysqli方法实现以下功能（php7）：

1、连接MySQL数据库服务器；
2、创建一个名为test的数据库；
3、在该数据库内创建一个名为“testTable”的数据表，数据表至少包含三个字段，字段名字、类型和属性自定；
4、为该数据库插入三条记录，并查询该数据表的所有数据；
5、修改其中的一条记录，并查询该数据表的所有数据；
6、删除其中的一条记录，并查询该数据表的所有数据；

mysqli方法实现连接数据库，及增删查改
";
	}
	else{
		echo "数据库连接失败！
";
	}


	$sql="CREATE DATABASE test";
	if (mysqli_query($con,$sql)){
	echo "数据库创建成功!
";
	}else{
	echo "数据库创建失败!
".mysqli_error($con)."
";
	}
	

	mysqli_select_db($con,"test");
	$table="CREATE TABLE testTable(
	student_id int(11) auto_increment primary key,
	student_no char(10) not null unique,
	student_name char(20) not null)";
	if(mysqli_query($con,$table)){
		echo "数据表创建成功!
";
	}
	else{
		echo "数据表创建失败!
".mysqli_error($con)."
";
	}
	
	$mysqli=new mysqli("localhost","root","15118595615","test");
	$query="select * from testTable";
	$insertdatas=mysqli_query($con,"insert into testTable(student_id,student_no,student_name) values('null','20170001','张三')");
	mysqli_free_result($insertdatas);
	$insertdatas=mysqli_query($con,"insert into testTable(student_id,student_no,student_name) values('null','20170002','李四')");
	mysqli_free_result($insertdatas);
	$insertdatas=mysqli_query($con,"insert into testTable(student_id,student_no,student_name) values('null','20170003','王五')");
	if($insertdatas){
		echo "数据插入成功！
";
		$result=$mysqli->query($query);
		foreach($result as $row){
			echo $row["student_id"].'  ';
			echo $row["student_no"].'  ';
			echo $row["student_name"]."
";
		}
	}
	else{
		echo "数据插入失败！
".mysqli_error($con)."
";
	}
	mysqli_free_result($insertdatas);


	$up=mysqli_query($con,"update testTable set student_no='20180001' where student_name='张三'");
	if($up){
		echo "数据更新成功!
";
		$result=$mysqli->query($query);
		foreach($result as $row){
			echo $row["student_id"].'  ';
			echo $row["student_no"].'  ';
			echo $row["student_name"]."
";
		}
	}
	else{
		echo "数据更新失败!
".mysqli_error($con)."
";
	}
	mysqli_free_result($up);


	$del=mysqli_query($con,"delete from testTable where student_name='李四'");
	if($del){
		echo "数据删除成功!
";
		$result=$mysqli->query($query);
		foreach($result as $row){
			echo $row["student_id"].'  ';
			echo $row["student_no"].'  ';
			echo $row["student_name"]."
";
		}
	}
	else{
		echo "数据删除失败!
".mysqli_error($con)."
";
	}
	mysqli_free_result($del);
	
	mysqli_close($con);
    ?>

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最终效果如下：
Detailed explanation of PHP7 database connection and addition, deletion, query and modification (mysqli method)
写代码的时候要注意PHP7和PHP5的一些差别：
1、PHP7要将PHP5的mysql（）换成mysqli（）；
2、PHP7的查询语句要写成mysqli（ $c o n n e c t,$ sql），PHP5的写法和PHP7的相反mysql（ $s q l ，$ connect）；

温馨提示：
每次查询完之后一定要用mysqli_free_result（）函数释放资源！不然会报错，无法执行下一条查询语句！初学的时候走了不少弯路，血的教训，希望能给初学的朋友帮助，少走弯路！

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