php 有什么方法可以检测 Laravel 中是否存在数据库表
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Is there any way to detect if a database table exists with Laravel
提问by Ehsan Zargar Ershadi
I want to be able to create a table using
我希望能够使用
Schema::create('mytable',function($table)
{
$table->increments('id');
$table->string('title');
});
But before that I would like to check if the table already exists, perhaps something like
但在此之前，我想检查该表是否已经存在，可能类似于
Schema::exists('mytable');
However, the above function does not exist. What else can I use?
但是，上述功能不存在。我还能用什么？
回答by Phill Sparks
If you are using Laravel 4 or 5 then there is the hasTable()method, you can find it in the L4 source codeor the L5 docs:
如果您使用的是 Laravel 4 或 5，则有该hasTable()方法，您可以在 L4 源代码或L5 文档中找到它：
Schema::hasTable('mytable');
回答by B. R. N. Rajoriya
To create a new table there is only one check by Laravel Schema function hasTable.
要创建一个新表，Laravel Schema 函数只需进行一项检查hasTable。
if (!Schema::hasTable('table_name')) {
// Code to create table
}
But if you want to drop any table before checking its existence then Schema have a function called dropIfExists.
但是如果你想在检查它存在之前删除任何表，那么 Schema 有一个名为dropIfExists.
Schema::dropIfExists('table_name');
It will drop the table if table will exist.
如果表存在，它将删除表。
回答by pankaj kumar
if you are using different connection then you have to go with my answer.
如果您使用不同的连接，那么您必须采用我的回答。
Schema::connection("bio_db")->hasTable('deviceLogs_11_2019')
here on hasTable()function you can pass more than 1 table name.
在hasTable()函数中，您可以传递 1 个以上的表名。
回答by mckendricks
No built in function for this in L3. You can do a raw query:
L3 中没有为此内置函数。您可以执行原始查询：
$table = "foo";
$check = DB::only('SELECT COUNT(*) as `exists`
FROM information_schema.tables
WHERE table_name IN (?)
AND table_schema = database()',$table);
if(!$check) // No table found, safe to create it.
{
// Schema::create …
}
回答by Bimal Poudel
Rather, depend on information schema query instead of checking for some data in the tables with COUNT().
相反，依赖于信息模式查询而不是检查表中的某些数据COUNT()。
SELECT table_schema
FROM information_schema.tables
WHERE table_schema = DATABASE()
AND table_name = 'table_name';
Change your 'table_name'value.
改变你的'table_name'价值。
If you get one row output, it means the table exists.
如果您得到一行输出，则表示该表存在。
