Yuav ua li cas saib cov xwm txheej thiab tus lej xov tooj cov ntaub ntawv cov qauv ntaub ntawv ntawm MySQL database?

MySQL Metadata

Tej zaum koj yuav xav paub peb hom lus hauv qab no txog MySQL:

• Query result information: Tus naj npawb ntawm cov ntaub ntawv cuam tshuam los ntawm SELECT, UPDATE lossis DELETE nqe lus.
• Cov ntaub ntawv hais txog databases thiab cov ntaub ntawv cov ntaub ntawv: Muaj cov qauv ntaub ntawv ntawm lub database thiab cov ntaub ntawv rooj.
• MySQL server cov ntaub ntawv: Muaj lub xeev tam sim no ntawm tus neeg rau zaub mov database, tus lej version, thiab lwm yam.

Hauv MySQL cov lus txib, peb tuaj yeem yooj yim tau txais cov ntaub ntawv saum toj no server.Tab sis yog tias koj siv cov lus sau ntawv xws li Perl lossis PHP, koj yuav tsum hu rau qhov tshwj xeeb interface kom tau txais nws.Tom ntej no peb yuav qhia kom meej.

Tau txais cov naj npawb ntawm cov ntaub ntawv cuam tshuam los ntawm nqe lus nug

PERL piv txwv

Hauv DBI scripts, tus naj npawb ntawm cov ntaub ntawv cuam tshuam los ntawm nqe lus tau xa rov qab los ntawm cov haujlwm ua ( ) lossis ua tiav ( ):

# 方法 1
# 使用do( ) 执行  $query 
my $count = $dbh->do ($query);
# 如果发生错误会输出 0
printf "%d 条数据被影响\n", (defined ($count) ? $count : 0);
# 方法 2
# 使用prepare( ) 及 execute( ) 执行  $query 
my $sth = $dbh->prepare ($query);
my $count = $sth->execute ( );
printf "%d 条数据被影响\n", (defined ($count) ? $count : 0);

PHP piv txwv

Hauv PHP, koj tuaj yeem siv mysqli_affected_rows() ua haujlwm kom tau txais cov ntaub ntawv muaj feem cuam tshuam los ntawm cov lus nug.

$result_id = mysqli_query ($conn_id, $query);
# 如果查询失败返回 
$count = ($result_id ? mysqli_affected_rows ($conn_id) : 0);
print ("$count 条数据被影响\n");

Daim ntawv teev cov databases thiab cov ntaub ntawv rooj

Koj tuaj yeem yooj yim tau txais cov npe ntawm cov ntaub ntawv thiab cov ntxhuav hauv MySQL server.Yog tias koj tsis muaj kev tso cai txaus, qhov tshwm sim yuav rov qab null.
Koj tuaj yeem siv SHOW TABLES lossis SHOW DATABASES nqe lus kom tau txais cov npe ntawm cov ntaub ntawv thiab cov ntaub ntawv.

PERL piv txwv

# 获取当前数据库中所有可用的表。
my @tables = $dbh->tables ( );
foreach $table (@tables ){
   print "表名 $table\n";
}

PHP piv txwv

Cov piv txwv hauv qab no tso tawm tag nrho cov databases ntawm MySQL server:

<?
php
$dbhost = 'localhost:3306'; // mysql服务器主机地址
$dbuser = 'root'; // mysql用户名
$dbpass = '123456'; // mysql用户名密码
$conn = mysqli_connect($dbhost, $dbuser, $dbpass);
if(! $conn )
{
 die('连接失败: ' . mysqli_error($conn));
}
// 设置编码，防止中文乱码
$db_list = mysqli_query($conn, 'SHOW DATABASES');
while ($db = mysqli_fetch_object($db_list))
{
 echo $db->Database . "<br />";
}
mysqli_close($conn);
?>

Tau txais cov metadata server

Cov lus hais hauv qab no tuaj yeem siv tau ntawm MySQL cov lus txib tam sim lossis hauv cov ntawv sau, xws li PHP scripts.