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PHP+MySql - Coding mã nguồn mở rât thông dụng để làm web, và hệ thống cơ sỏ dữ liệu rất mạnh duợc ưa chuộng

SQL coding examples - ví dụ về data sql

SQL coding examples
This SQL and PHP will count how many rows contain unique elements in your database. For example, you may have a database of user entries and want to know how many entries each user has. In this example, you want to know how many rows contain each unique element "name":

Code: :

$query = mysql_query("SELECT name, COUNT(*) AS number FROM $table GROUP BY name");
if ( mysql_num_rows($query) == 0 ) echo "No rows in the database";
while ($row = mysql_fetch_array($query)) {
$name = $row['name'] ;
$count = $row['number'] ;
echo "$name has $count rows in the database<br>";
}

Use this to take a single table backup, with elements in double quotes delimited with a comma:

Code: :

while ($row = mysql_fetch_array($query,MYSQL_NUM)) $output .= "\"" . implode("\",\"",str_replace("\r\n"," ",$row)) . "\"\r\n"; echo $output; // or write $output to a file

Use this to count the rows that meet a select criteria. You can use any WHERE criteria you wish, or none (as in the example below which counts the total rows).

Code: :

$query = mysql_query("SELECT COUNT(*) AS number FROM $table LIMIT 1");
$row = mysql_fetch_array($query);
if ($row['number'] > 1000 ) echo "You have over 1,000 rows";

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