在MySQL中模拟删除级联？
是否可以自动预测删除级联之后的操作？在我的软件中，我想给用户一个警告，其中包含将被删除的数据的详细信息。您可以复制数据库，并在删除后在在MySQL中模拟删除级联？,mysql,cascading-deletes,Mysql,Cascading Deletes,是否可以自动预测删除级联之后的操作？在我的软件中，我想给用户一个警告，其中包含将被删除的数据的详细信息。您可以复制数据库，并在删除后在上放置触发器 DELIMITER $$ CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW BEGIN INSERT INTO log VALUES (null /*autoinc id*/ , 'table1'
上放置触发器
DELIMITER $$
CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW
BEGIN
INSERT INTO log VALUES (null /*autoinc id*/
, 'table1' /*tablename*/
, old.id /*tableid*/
, concat_ws(',',old.field1,old.field2 /*CSV's of fields*/
, NOW() /*timestamp*/
, 'delete'); /*what action*/
REPLACE INTO restore_table1 VALUES (old.id,
, old.field1
, old.field2
, ... );
END $$
DELIMITER ;
日志表只是包含以下字段的表：
id integer autoincrement primary key
tablename varchar(45)
table_id integer
fields varchar(6000)
delete_time timestamp
action enum('insert','update','delete')
如果在副本的删除级联之前执行操作，请从日志中选择@last_id:=max（id）。
然后您可以从日志中选择*，其中id>@last\u id
并获取将在级联中删除的所有行
之后，您可以使用restore_table1在复制数据库中重新创建级联中删除的行。您可以复制数据库，并在删除后在上放置触发器
DELIMITER $$
CREATE TRIGGER ad_table1_each AFTER DELETE ON table1 FOR EACH ROW
BEGIN
INSERT INTO log VALUES (null /*autoinc id*/
, 'table1' /*tablename*/
, old.id /*tableid*/
, concat_ws(',',old.field1,old.field2 /*CSV's of fields*/
, NOW() /*timestamp*/
, 'delete'); /*what action*/
REPLACE INTO restore_table1 VALUES (old.id,
, old.field1
, old.field2
, ... );
END $$
DELIMITER ;
日志表只是包含以下字段的表：
id integer autoincrement primary key
tablename varchar(45)
table_id integer
fields varchar(6000)
delete_time timestamp
action enum('insert','update','delete')
如果在副本的删除级联之前执行操作，请从日志中选择@last_id:=max（id）。
然后您可以从日志中选择*，其中id>@last\u id
并获取将在级联中删除的所有行
之后，您可以使用restore_table1在复制数据库中重新创建级联中删除的行。我认为您可以将Johan的触发器解决方案与回滚的事务结合使用。这避免了需要第二个数据库和手动恢复已删除的条目
- 添加触发器和日志表
- 对于每次尝试的删除，启动一个事务并删除条目
- 将日志中的信息提交给用户以供批准
- 如果用户同意提交事务，否则回滚
我认为您可以将Johan的触发器解决方案与回滚的事务结合使用。这避免了需要第二个数据库和手动恢复已删除的条目
- 添加触发器和日志表
- 对于每次尝试的删除，启动一个事务并删除条目
- 将日志中的信息提交给用户以供批准
- 如果用户同意提交事务，否则回滚
我写了一个非常快速的hack，它完全满足您在PHP中的需要，因为我想做完全相同的事情，但还没有在网上找到任何相关资源
对你来说可能太晚了，但它可能会帮助别人
function get_referencing_foreign_keys ($database, $table) {
$query = 'SELECT TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_SCHEMA = "'.$database.'" AND REFERENCED_TABLE_NAME = '.esc($table);
$result = rquery($query);
$foreign_keys = array();
while ($row = mysql_fetch_row($result)) {
$foreign_keys[] = array('database' => $row[0], 'table' => $row[1], 'column' => $row[2], 'reference_column' => $row[3]);
}
return $foreign_keys;
}
function get_foreign_key_deleted_data_html ($database, $table, $where) {
$data = get_foreign_key_deleted_data ($database, $table, $where);
$html = '';
foreach ($data as $key => $this_data) {
$html .= "<h2>$key</h2>\n";
$html .= "<table>\n";
$i = 0;
foreach ($this_data as $value) {
if($i == 0) {
$html .= "\t<tr>\n";
foreach ($value as $column => $column_value) {
$html .= "\t\t<th>".htmlentities($column)."</th>\n";
}
$html .= "\t</tr>\n";
}
$html .= "\t<tr>\n";
foreach ($value as $column => $column_value) {
$html .= "\t\t<td>".htmlentities($column_value)."</td>\n";
}
$html .= "\t</tr>\n";
$i++;
}
$html .= "</table>\n";
}
return $html;
}
function get_foreign_key_deleted_data ($database, $table, $where) {
$GLOBALS['get_data_that_would_be_deleted'] = array();
$data = get_data_that_would_be_deleted($database, $table, $where);
$GLOBALS['get_data_that_would_be_deleted'] = array();
return $data;
}
function get_data_that_would_be_deleted ($database, $table, $where, $recursion = 100) {
if($recursion <= 0) {
die("Deep recursion!");
}
if($recursion == 100) {
$GLOBALS['get_data_that_would_be_deleted'] = array();
}
if($table) {
if(is_array($where)) {
$foreign_keys = get_referencing_foreign_keys($database, $table);
$data = array();
$query = 'SELECT * FROM `'.$table.'`';
if(count($where)) {
$query .= ' WHERE 1';
foreach ($where as $name => $value) {
$query .= " AND `$name` = ".esc($value);
}
}
$result = rquery($query);
$to_check = array();
while ($row = mysql_fetch_row($result)) {
$new_row = array();
$i = 0;
foreach ($row as $this_row) {
$field_info = mysql_fetch_field($result, $i);
$new_row[$field_info->name] = $this_row;
foreach ($foreign_keys as $this_foreign_key) {
if($this_foreign_key['reference_column'] == $field_info->name) {
$to_check[] = array('value' => $this_row, 'foreign_key' => array('table' => $this_foreign_key['table'], 'column' => $this_foreign_key['column'], 'database' => $this_foreign_key['database']));
}
}
$i++;
}
$GLOBALS['get_data_that_would_be_deleted'][$table][] = $new_row;
}
foreach ($to_check as $this_to_check) {
if(isset($this_to_check['value']) && !is_null($this_to_check['value'])) {
get_data_that_would_be_deleted($database, $this_to_check['foreign_key']['table'], array($this_to_check['foreign_key']['column'] => $this_to_check['value']), $recursion - 1);;
}
}
$data = $GLOBALS['get_data_that_would_be_deleted'];
return $data;
} else {
die("\$where needs to be an array with column_name => value pairs");
}
} else {
die("\$table was not defined!");
}
}
它将打印一个完整的表，其中包含所有要删除的行和值
但正如我所说，这是一个非常、非常快速和肮脏的黑客行为。我很高兴有任何bug报告（当然有很多！）。我写了一个非常快速的hack，它完全符合PHP的需要，因为我想做完全相同的事情，但还没有在网上找到任何相关资源
对你来说可能太晚了，但它可能会帮助别人
function get_referencing_foreign_keys ($database, $table) {
$query = 'SELECT TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE REFERENCED_TABLE_SCHEMA = "'.$database.'" AND REFERENCED_TABLE_NAME = '.esc($table);
$result = rquery($query);
$foreign_keys = array();
while ($row = mysql_fetch_row($result)) {
$foreign_keys[] = array('database' => $row[0], 'table' => $row[1], 'column' => $row[2], 'reference_column' => $row[3]);
}
return $foreign_keys;
}
function get_foreign_key_deleted_data_html ($database, $table, $where) {
$data = get_foreign_key_deleted_data ($database, $table, $where);
$html = '';
foreach ($data as $key => $this_data) {
$html .= "<h2>$key</h2>\n";
$html .= "<table>\n";
$i = 0;
foreach ($this_data as $value) {
if($i == 0) {
$html .= "\t<tr>\n";
foreach ($value as $column => $column_value) {
$html .= "\t\t<th>".htmlentities($column)."</th>\n";
}
$html .= "\t</tr>\n";
}
$html .= "\t<tr>\n";
foreach ($value as $column => $column_value) {
$html .= "\t\t<td>".htmlentities($column_value)."</td>\n";
}
$html .= "\t</tr>\n";
$i++;
}
$html .= "</table>\n";
}
return $html;
}
function get_foreign_key_deleted_data ($database, $table, $where) {
$GLOBALS['get_data_that_would_be_deleted'] = array();
$data = get_data_that_would_be_deleted($database, $table, $where);
$GLOBALS['get_data_that_would_be_deleted'] = array();
return $data;
}
function get_data_that_would_be_deleted ($database, $table, $where, $recursion = 100) {
if($recursion <= 0) {
die("Deep recursion!");
}
if($recursion == 100) {
$GLOBALS['get_data_that_would_be_deleted'] = array();
}
if($table) {
if(is_array($where)) {
$foreign_keys = get_referencing_foreign_keys($database, $table);
$data = array();
$query = 'SELECT * FROM `'.$table.'`';
if(count($where)) {
$query .= ' WHERE 1';
foreach ($where as $name => $value) {
$query .= " AND `$name` = ".esc($value);
}
}
$result = rquery($query);
$to_check = array();
while ($row = mysql_fetch_row($result)) {
$new_row = array();
$i = 0;
foreach ($row as $this_row) {
$field_info = mysql_fetch_field($result, $i);
$new_row[$field_info->name] = $this_row;
foreach ($foreign_keys as $this_foreign_key) {
if($this_foreign_key['reference_column'] == $field_info->name) {
$to_check[] = array('value' => $this_row, 'foreign_key' => array('table' => $this_foreign_key['table'], 'column' => $this_foreign_key['column'], 'database' => $this_foreign_key['database']));
}
}
$i++;
}
$GLOBALS['get_data_that_would_be_deleted'][$table][] = $new_row;
}
foreach ($to_check as $this_to_check) {
if(isset($this_to_check['value']) && !is_null($this_to_check['value'])) {
get_data_that_would_be_deleted($database, $this_to_check['foreign_key']['table'], array($this_to_check['foreign_key']['column'] => $this_to_check['value']), $recursion - 1);;
}
}
$data = $GLOBALS['get_data_that_would_be_deleted'];
return $data;
} else {
die("\$where needs to be an array with column_name => value pairs");
}
} else {
die("\$table was not defined!");
}
}
它将打印一个完整的表，其中包含所有要删除的行和值
但正如我所说，这是一个非常、非常快速和肮脏的黑客行为。我很高兴看到任何错误报告（当然有很多！）。好问题，我也对答案感兴趣。目前我能想到的唯一合理方法是显示中的完整列，然后遍历到相应的表中。。。（硬代码fkey_名称=>表名称…）好问题，我也对答案感兴趣。目前我能想到的唯一合理方法是显示
中的完整列，然后遍历到相应的表中。。。（硬代码fkey_names=>table_names…）唯一的问题是，如果您登录的引擎也支持事务，那么日志记录也将回滚，因此您需要使用非事务性引擎进行日志记录，如MyISAM。事务想法非常好。事实上，我既不使用触发器也不使用日志。我只是模拟删除，然后回滚。@user694971:如果您想向用户显示删除的条目，我想您需要日志。如果没有它，您只能显示剩余的条目，除非您的应用程序逻辑能够解决这个问题。唯一的问题是，如果您登录的引擎也支持事务，那么日志记录也将回滚，因此您需要使用非事务性引擎来记录，如MyISAM。事务想法非常好。事实上，我既不使用触发器也不使用日志。我只是模拟删除，然后回滚。@user694971:如果您想向用户显示删除的条目，我想您需要日志。如果没有它，您只能显示其余的条目，除非您的应用程序逻辑能够解决这个问题。