PHP single row from scratch (13) Using PHP to display data from MySQL database_PHP tutorial

1. Execute SQL statements in PHP

To obtain data from the database, PHP must first execute a SQL statement that operates on the table, including SELECT, INSERT, UPDATE or DELETE statements. Under normal circumstances, when executing a SELECT statement in PHP, some record rows will be found from the table. When executing other statements, only information about whether the statement was successfully executed will be returned.

<?php
$host='localhost';
$user_name='root';
$password='helloworld';
$conn=mysql_connect($host,$user_name,$password);//连接MySQL
if(!$conn)
{
	die('FAIL!'.mysql_error());
}
mysql_select_db('test');//选择数据库
$sql='select UserId,UserName,Gender from users';
$result=mysql_query($sql);//获取查询结果
if($result)
{
	echo 'SQLsyntex:'.$sql.'<br/>Success';
	$num=mysql_num_rows($result);//获取查询结果的行数
	echo '<br/> select <b>'.$num.'   </b>rows';
}
mysql_close($conn);
?>

Usually, mysql_query() is also used together with mysql_error(), so that when there is a problem with the execution of the SQL statement, the cause of the problem can be found based on the information generated by mysql_error().

<?php
$host='localhost';
$user_name='root';
$password='helloworld';
$conn=mysql_connect($host,$user_name,$password);
if(!$conn)
{
	die('FAIL!'.mysql_error());
}
mysql_select_db('test');
$sql='select UserId,UserName,Gender,cc from users';
$result=mysql_query($sql) OR die("<br/>ERROR:<b>".mysql_error()."</b><br/><br/><br/>Problem:<br/>.$sql");
if($result)
{
	echo 'SQLsyntex:'.$sql.'<br/>Success';
	$num=mysql_num_rows($result);
	echo '<br/> select <b>'.$num.'   </b>rows';
}
mysql_close($conn);
?>

2. Use PHP to process data result sets

After a SQL statement is successfully executed in the program, you can use mysql_fetch_array() to obtain the specific query results, that is, use this function to obtain the field values ​​of the record.

<?php
$host='localhost';
$user_name='root';
$password='helloworld';
$conn=mysql_connect($host,$user_name,$password);
if(!$conn)
{
	die('FAIL!'.mysql_error());
}
mysql_select_db('test');
$sql='select id,name,sex,age from users';
$result=mysql_query($sql) OR die("<br/>ERROR:<b>".mysql_error()."</b><br/><br/><br/>Problem:<br/>.$sql");
if($num=mysql_num_rows($result))
{
	$row=mysql_fetch_array($result);
	echo '<pre class="code">';
	print_r($row);
}
mysql_close($conn);
?>

The function mysql_fetch_array() tells that this function returns a row in the result set and treats it as an associative array or a normal array. By default, the returned array is both. The array returned by mysql_fetch_array() has two indexes for each field value: one is indexed by number, and the other is indexed by field name.

<?php
$host='localhost';
$user_name='root';
$password='helloworld';
$conn=mysql_connect($host,$user_name,$password);
if(!$conn)
{
	die('FAIL!'.mysql_error());
}
mysql_select_db('test');
$sql='select id,name,sex,age from users';
$result=mysql_query($sql) OR die("<br/>ERROR:<b>".mysql_error()."</b><br/><br/><br/>Problem:<br/>.$sql");
if($num=mysql_num_rows($result))
{
	$row=mysql_fetch_array($result);
	echo '<pre class="code">';
	while($row=mysql_fetch_array($result,MYSQL_ASSOC))
	{print_r($row);
	}
}
mysql_close($conn);
?>

Use a while loop to call the function mysql_fetch_array() multiple times, assign the array returned by the call to the variable $row each time, and then output the array variable $row in the loop body. When calling the function mysql_fetch_array(), specify the second parameter as MYSQL_ASSOC, so the result set array returned is an associative array indexed by the field name.

http://www.bkjia.com/PHPjc/765067.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/765067.htmlTechArticle1. To execute a SQL statement in PHP to obtain data from the database, PHP must first execute a SQL statement that operates on the table. , including SELECT, INSERT, UPDATE or DELETE statements. Generally speaking, in PHP...