laravel 如何删除多列上的唯一键？
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How to delete Unique key on multiple columns?
提问by Favourite Onwuemene
How do I reverse a unique key added on multiple columns in Laravel? Basically, what should go in the down() function of this migration code:
如何反转在 Laravel 中的多列上添加的唯一键？基本上，这个迁移代码的 down() 函数应该包含什么：
public function up()
{
Schema::table('topics', function($table)
{
$table->unique(array('subject_id', 'grade_id', 'semester_id', 'name'));
}
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::table('topics', function($table)
{
}
}
回答by Marwelln
To drop a unique index, you use dropUnique('name_of_index').
要删除唯一索引，请使用dropUnique('name_of_index').
If you're not specifying an index name in the second parameter of unique(), the name of the index will be tableName_fieldsSeperatedByUnderscore_unique.
如果您没有在 的第二个参数中指定索引名称，则索引名称unique()将为tableName_fieldsSeperatedByUnderscore_unique。
public function down()
{
Schema::table('topics', function($table)
{
$table->dropUnique('topics_subject_id_grade_id_semester_id_name_unique');
}
}
回答by VIjay J
There are two approaches to drop unique index :
有两种方法可以删除唯一索引：
First Approach : In dropUnique() function we can pass array so that you don't need to use exact unique index name like "tableName_fieldsSeperatedByUnderscore_unique". Here is code snippet
第一种方法：在 dropUnique() 函数中，我们可以传递数组，这样您就不需要使用精确的唯一索引名称，例如“tableName_fieldsSeperatedByUnderscore_unique”。这是代码片段
Schema::table('users', function (Blueprint $table) {
$table->dropUnique(['email']);
});
This will drop the unique index of column 'email'.
这将删除列“电子邮件”的唯一索引。
Second Approach: This approach is exactly same as described by Marwelln,still I would like to put it here again. You can pass unique index name in the dropUnique(), it will also work. But be sure that you are confident about unique index name.Code for that looks like this:
第二种方法：这种方法与Marwelln描述的完全相同，我仍然想再次放在这里。您可以在 dropUnique() 中传递唯一索引名称，它也可以工作。但请确保您对唯一索引名称充满信心。代码如下所示：
Schema::table('users', function (Blueprint $table) {
$table->dropUnique('users_email_unique');
});
