php - Cascade on delete sql -

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this question has answer here:

im working on small website involves use of databases, i'm using 2 tables users, in first table add users , information, , in second 1 add user id course id.

my question how can add cascade on delete, in table?

create table if not exists `students` (   `studentid` int(11) not null auto_increment,   `fname` varchar(255) collate utf8_unicode_ci not null,   `lname` varchar(64) collate utf8_unicode_ci not null,   `studentcode` varchar(16) collate utf8_unicode_ci not null,   `courseid` int(11) not null,   primary key (`studentid`) ) engine=innodb  default charset=utf8 collate=utf8_unicode_ci auto_increment=27 ;  create table if not exists `idtables` (   `id` int(11) not null auto_increment,   `courseid` varchar(255) collate utf8_unicode_ci not null,   `studentid` char(64) collate utf8_unicode_ci not null,   primary key (`id`) ) engine=innodb  default charset=utf8 collate=utf8_unicode_ci auto_increment=43 ;

you need define behaviour in foreign key constraint like:

create table if not exists `idtables` (   `id` int(11) not null auto_increment,   `courseid` varchar(255) collate utf8_unicode_ci not null,   `studentid` char(64) collate utf8_unicode_ci not null,   primary key (`id`),   foreign key fk_students_id (studentid)     references students (id)     on delete cascade     on update cascade ) engine=innodb  default charset=utf8 collate=utf8_unicode_ci auto_increment=43 ;

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