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Collection::existsInDatabase — Check if collection exists in database
Checks if the Collection object refers to a collection in the database (schema).
此函數沒(méi)有參數。
Returns true if collection exists in the database, else false if it does not.
A table defined with two columns (doc and _id) is considered a collection, and a third _json_schema column as of MySQL 8.0.21. Adding an additional column means existsInDatabase() will no longer see it as a collection.
示例 #1 mysql_xdevapi\Collection::existsInDatabase() example
<?php
$session = mysql_xdevapi\getSession("mysqlx://user:password@localhost");
$session->sql("DROP DATABASE IF EXISTS addressbook")->execute();
$session->sql("CREATE DATABASE addressbook")->execute();
$schema = $session->getSchema("addressbook");
$create = $schema->createCollection("people");
// ...
$collection = $schema->getCollection("people");
// ...
if (!$collection->existsInDatabase()) {
echo "The collection no longer exists in the database named addressbook. What happened?";
}
?>