wordpress数据库操作类wpdb相关注释说明

以下相关代码注释可能不全面，有不对的地方，仅做参考；
show_errors();// 是否显示sql/DB的错误开关 默认是false 关闭的

$this->init_charset();

$this->dbuser = $dbuser;
$this->dbpassword = $dbpassword;
$this->dbname = $dbname;
$this->dbhost = $dbhost;

$this->db_connect();
}
//类析构函数
function __destruct() {
return true;
}
//设置编码变量
function init_charset() {
if ( function_exists(‘is_multisite’) && is_multisite() ) {
$this->charset = ‘utf8’;
if ( defined( ‘DB_COLLATE’ ) && DB_COLLATE )
$this->collate = DB_COLLATE;
else
$this->collate = ‘utf8_general_ci’;
} elseif ( defined( ‘DB_COLLATE’ ) ) {
$this->collate = DB_COLLATE;
}

if ( defined( ‘DB_CHARSET’ ) )
$this->charset = DB_CHARSET;
}
// 设置数据库查询编码
function set_charset($dbh, $charset = null, $collate = null) {
if ( !isset($charset) )
$charset = $this->charset;
if ( !isset($collate) )
$collate = $this->collate;
if ( $this->has_cap( ‘collation’, $dbh ) && !empty( $charset ) ) {
if ( function_exists( ‘mysql_set_charset’ ) && $this->has_cap( ‘set_charset’, $dbh ) ) {
mysql_set_charset( $charset, $dbh );
$this->real_escape = true;
} else {
$query = $this->prepare( ‘SET NAMES %s’, $charset );
if ( ! empty( $collate ) )
$query .= $this->prepare( ‘ COLLATE %s’, $collate );
mysql_query( $query, $dbh );
}
}
}

// 设置表前缀
function set_prefix( $prefix, $set_table_names = true ) {
……….
}

//设置博客id
function set_blog_id( $blog_id, $site_id = 0 ) {
……………
}

//获取博客前缀
function get_blog_prefix( $blog_id = null ) {
if ( is_multisite() ) {
if ( null === $blog_id )
$blog_id = $this->blogid;
$blog_id = (int) $blog_id;
if ( defined( ‘MULTISITE’ ) && ( 0 == $blog_id || 1 == $blog_id ) )
return $this->base_prefix;
else
return $this->base_prefix . $blog_id . ‘_’;
} else {
return $this->base_prefix;
}
}
//返回一个数组的Word Press表
function tables( $scope = ‘all’, $prefix = true, $blog_id = 0 ) {
……………
}

//选择数据库
function select( $db, $dbh = null) {
if ( is_null($dbh) )
$dbh = $this->dbh;

if ( !@mysql_select_db( $db, $dbh ) ) {
$this->ready = false;
$this->bail( sprintf( /*WP_I18N_DB_SELECT_DB*/’

无法选择数据库

我们可以和数据库服务器建立连接（说明您提供的用户名和密码正确），但无法选择（select） %1$s 数据库。

• 您确认数据库存在？
• 您确认用户 %2$s 拥有使用 %1$s 数据库的权限？
• 在某些系统上您的数据库名可能还包含了您用户名的前缀，例如 username_%1$s，问题会不会出在这里？

如果您不知道如何设置一个数据库，您应该联系您的主机管理员。如果所有办法还没有解决您的问题，您可以在 https://zh-cn.forums.wordpress.org/”>WordPress 中

文论坛上寻求帮助。

‘/*/WP_I18N_DB_SELECT_DB*/, $db, $this->dbuser ), ‘db_select_fail’ );
return;
}
}

//对特殊字符转义
function _weak_escape( $string ) {
return addslashes( $string );
}

//判断$this->real_escape为true还是false，true就用数据库转义mysql_real_escape_string()，否则用addslashes
/*mysql_real_escape_string 优于addslashes
mysql_real_escape_string考虑到字符集的问题
mysql_real_escape_string最好与mysql_set_charset一起使用因为都涉及字符集的问题，mysql_set_charset而是设字符集的
*/
function _real_escape( $string ) {
if ( $this->dbh && $this->real_escape )
return mysql_real_escape_string( $string, $this->dbh );
else
return addslashes( $string );
}

//字符串数组转义
function _escape( $data ) {
if ( is_array( $data ) ) {
foreach ( (array) $data as $k => $v ) {
if ( is_array($v) )
$data[$k] = $this->_escape( $v );
else
$data[$k] = $this->_real_escape( $v );
}
} else {
$data = $this->_real_escape( $data );
}

return $data;
}

//内容转义（是否为数组）
function escape( $data ) {
if ( is_array( $data ) ) {
foreach ( (array) $data as $k => $v ) {
if ( is_array( $v ) )
$data[$k] = $this->escape( $v );
else
$data[$k] = $this->_weak_escape( $v );
}
} else {
$data = $this->_weak_escape( $data );
}

return $data;
}

function escape_by_ref( &$string ) {
$string = $this->_real_escape( $string );
}

//数据执行代码安全保障
function prepare( $query = null ) { // ( $query, *$args )
if ( is_null( $query ) )
return;

$args = func_get_args();
array_shift( $args );
// If args were passed as an array (as in vsprintf), move them up
if ( isset( $args[0] ) && is_array($args[0]) )
$args = $args[0];
$query = str_replace( “‘%s'”, ‘%s’, $query ); // in case someone mistakenly already singlequoted it
$query = str_replace( ‘”%s”‘, ‘%s’, $query ); // doublequote unquoting
$query = preg_replace( ‘|(?show_errors;
$this->show_errors = $show;
return $errors;
}

//设置隐藏错误信息
function hide_errors() {
$show = $this->show_errors;
$this->show_errors = false;
return $show;
}
//是否抑制错误信息
function suppress_errors( $suppress = true ) {
$errors = $this->suppress_errors;
$this->suppress_errors = (bool) $suppress;
return $errors;
}

function flush() {
$this->last_result = array();
$this->col_info    = null;
$this->last_query  = null;
}

//数据库连接
function db_connect() {
………
}

//数据库执行语句
function query( $query ) {
$return_val     = $num_rows;
}

return $return_val;
}

//数据库插入
function insert( $table, $data, $format = null ) {
return $this->_insert_replace_helper( $table, $data, $format, ‘INSERT’ );
}

//数据替换
function replace( $table, $data, $format = null ) {
return $this->_insert_replace_helper( $table, $data, $format, ‘REPLACE’ );
}

//数据插入有insert into和replace into两种
function _insert_replace_helper( $table, $data, $format = null, $type = ‘INSERT’ ) {
if ( ! in_array( strtoupper( $type ), array( ‘REPLACE’, ‘INSERT’ ) ) )
return false;
$formats = $format = (array) $format;
$fields = array_keys( $data );
$formatted_fields = array();
foreach ( $fields as $field ) {
if ( !empty( $format ) )
$form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
elseif ( isset( $this->field_types[$field] ) )
$form = $this->field_types[$field];
else
$form = ‘%s’;
$formatted_fields[] = $form;
}
$sql = “{$type} INTO `$table` (`” . implode( ‘`,`’, $fields ) . “`) VALUES (‘” . implode( “‘,'”, $formatted_fields ) . “‘)”;
return $this->query( $this->prepare( $sql, $data ) );
}

//数据库更新
function update( $table, $data, $where, $format = null, $where_format = null ) {
………….
}

//取得执行语句的相关数组信息
function get_var( $query = null, $x = 0, $y = 0 ) {
$this->func_call = “$db->get_var(“$query”, $x, $y)”;
if ( $query )
$this->query( $query );

// Extract var out of cached results based x,y vals
if ( !empty( $this->last_result[$y] ) ) {
$values = array_values( get_object_vars( $this->last_result[$y] ) );
}

// If there is a value return it else return null
return ( isset( $values[$x] ) && $values[$x] !== ” ) ? $values[$x] : null;
}

//取得一行数据信息
function get_row( $query = null, $output = OBJECT, $y = 0 ) {
$this->func_call = “$db->get_row(“$query”,$output,$y)”;
if ( $query )
$this->query( $query );
else
return null;

if ( !isset( $this->last_result[$y] ) )
return null;

if ( $output == OBJECT ) {
return $this->last_result[$y] ? $this->last_result[$y] : null;
} elseif ( $output == ARRAY_A ) {
return $this->last_result[$y] ? get_object_vars( $this->last_result[$y] ) : null;
} elseif ( $output == ARRAY_N ) {
return $this->last_result[$y] ? array_values( get_object_vars( $this->last_result[$y] ) ) : null;
} else {
$this->print_error(/*WP_I18N_DB_GETROW_ERROR*/’ $db->get_row(string query, output type, int offset) —— 输出类型需为 OBJECT、ARRAY_A，或

ARRAY_N’/*/WP_I18N_DB_GETROW_ERROR*/);
}
}

//获得一列数据执行结果
function get_col( $query = null , $x = 0 ) {
if ( $query )
$this->query( $query );

$new_array = array();
// Extract the column values
for ( $i = 0, $j = count( $this->last_result ); $i < $j; $i++ ) {    $new_array[$i] = $this->get_var( null, $x, $i );
}
return $new_array;
}

//返回整个执行结果
function get_results( $query = null, $output = OBJECT ) {
……….
}

//取得最后一次结果集中的一列信息
function get_col_info( $info_type = ‘name’, $col_offset = -1 ) {
…………….
}

//计时器开始
function timer_start() {
$mtime            = explode( ‘ ‘, microtime() );
$this->time_start = $mtime[1] + $mtime[0];
return true;
}
//计时结束返回总共时间
function timer_stop() {
$mtime      = explode( ‘ ‘, microtime() );
$time_end   = $mtime[1] + $mtime[0];
$time_total = $time_end – $this->time_start;
return $time_total;
}
//在头部和尾部中包含错误信息
function bail( $message, $error_code = ‘500’ ) {
if ( !$this->show_errors ) {
if ( class_exists( ‘WP_Error’ ) )
$this->error = new WP_Error($error_code, $message);
else
$this->error = $message;
return false;
}
wp_die($message);
}
//数据库版本检查
function check_database_version() {
global $wp_version, $required_mysql_version;
// Make sure the server has the required MySQL version
if ( version_compare($this->db_version(), $required_mysql_version, ‘<') ) return new WP_Error('database_version', sprintf( __( 'ERROR: WordPress %1$s requires MySQL %2$s or higher’ ), $wp_version,

$required_mysql_version ));
}

//是否数据库需要升级
function supports_collation() {
return $this->has_cap( ‘collation’ );
}

//确定一个数据库支持特定功能
function has_cap( $db_cap ) {
$version = $this->db_version();

switch ( strtolower( $db_cap ) ) {
case ‘collation’ :    // @since 2.5.0
case ‘group_concat’ : // @since 2.7
case ‘subqueries’ :   // @since 2.7
return version_compare( $version, ‘4.1’, ‘>=’ );
case ‘set_charset’ :
return version_compare($version, ‘5.0.7’, ‘>=’);
};

return false;
}
//返回调用函数的名称字符串
function get_caller() {
$trace  = array_reverse( debug_backtrace() );
$caller = array();

foreach ( $trace as $call ) {
if ( isset( $call[‘class’] ) && __CLASS__ == $call[‘class’] )
continue; // Filter out wpdb calls.
$caller[] = isset( $call[‘class’] ) ? “{$call[‘class’]}->{$call[‘function’]}” : $call[‘function’];
}

return join( ‘, ‘, $caller );
}
//取得数据库版本信息
function db_version() {
return preg_replace( ‘/[^0-9.].*/’, ”, mysql_get_server_info( $this->dbh ) );
}
}

?>