MySQL trigger and jQuery selector
Blogs20112011-03-19
MySQL: Trigger
Suppose we have 3 tables, 1 master table t1 and 2 slave tables: t2, t3. They are associated with column ‘name’. When record in master table t1 is deleted, the assciated records in t2 and t3 should be deleted either. This is where the trigger used.
The following is my cascade delete trigger example:
delimiter //
create trigger delete_3cascade_tables
after
delete on t1 for each row
begin
delete from t2 where name=OLD.name;
delete from t3 where name=OLD.name;
end;//
delimiter ;It works fine. By the way, if want to check this trigger, use the following sql:
select * from information_schema.triggers
where trigger_schema='Database_Where_Triggers_In';jQuery: Auto refresh table’s td column
I have the following html table to list data from MySQL DB.
<table>
<tr>
<td>...</td>
<td><form method="post" action="<?=$this->url;?>" id="f_<?=$row['id'];?>">
<textarea name="comments"
onchange="MyFakeClass.comment('f_<?=$row['id'];?>')">
<?=$row['comment'];?></textarea>
<input type="hidden" name="id" value="<?=$row['id'];?>" />
</form>
</td>
<td><label><?=$row['username']?$row['username']:'N/A';?></label></td>
</tr>
</table>When user edits the textarea column, the editing comment is auto stored in MySQL table, also refreshes the next that marks which users does the editing.
Ajax is good. By using ‘onchange=“MyFakeClass.comment(‘f_’)”>’, when comment changes, some magic steps are done to control screen and dynamic data in Ajax Style. The following is my simple snippet; it implements the above 2 functions: submit form and refresh screen.
MyFakeClass = {
...
comment : function(fid) {
$.post(MyFakeClass.url, $('#'+fid).serialize(), function(data) {
$('#'+fid).parent().parent().find('td:last label').text(data);
});
return false;
}
}- Here use form for 2 things: uses it’s post method; adds a hidden field to pass id. An alternative way to do so is manually processing textarea by using $.trigger() without form.
- MyFakeClass.url = $(’#‘+fid).attr(‘action’); This makes it standard to make the form readable.
- Function comment() returns false is a ncessary: So the
- When form submit, the value in will be auto updated based on Ajax Response; same as the