How to query the number of records in php mysql

php Mysql method of querying the number of records: 1. Count directly when querying, with statements such as "$count=$result['count'];"; 2. Take out first, then count, with statements such as "$ count=mysql_num_rows($result);”.

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PHP queries the number of records that meet the conditions in the database (Two implementation methods)

When you need to output the number of website user registrations or determine whether there are duplicate records before inserting data, you need to obtain the number of records that meet the conditions of the MySQL query. The following two methods are introduced Query statistical methods.

The first method: direct statistics when querying

The code is as follows:

$sql="SELECT COUNT(*) AS count FROM TABLE WHERE id='$id'"; 
$result=mysql_fetch_array(mysql_query($sql)); 
$count=$result['count'];

The second method: take out first, then count

The code is as follows:

$sql="SELECT * FROM TABLE WHERE id='$id'"; 
$result=mysql_fetch_array(mysql_query($sql)); 
$count=count($result);//或者$count=mysql_num_rows($result);

However, when using MySQL's COUNT(*) directly, the efficiency advantage is very significant when the amount of data is huge. Because the latter requires secondary calculation, it is better to use the former to count data items. registration.

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