PHP PDO新连接：选择数据库有什么影响？

When making a new connection with PDO:

$conn = new PDO( DB_DSN, DB_USERNAME, DB_PASSWORD );

It appears you have to specify a database in the DB_DSN, e.g.

mysql:dbname=mydatabase

I have however just discovered that this does not limit subsequent queries using this connection to just this database. Any other databases that DB_USERNAME has permissions for can be used. All it appears to do is specify a default.

It has revealed for me that sometimes, queries were not being specific enough and thus a risk that a table in the wrong database would be accessed.

I am thinking I should create a dummy database, make all connections to that database, thus forcing all queries to include the database name explicitly.

Or: is there a way to make a connection exclusive to a given database?

What is best practice here?

Options on that:

• use db name in querys SELECT * FROM dbname.tblname
• create an sql mapper class that selects the database before each query new SQLMapper($databasename,$connection); & mysql_select_db($this->dbname,$this->con) in query() method
• use DOCTRINE or something like that, they handle that for you
• give an dbuser only access to one database (forces devs to use the right instance & no db change)

Use what is usefull in given cases, there is no best solution.

Its mostly about how much control over the code in your application you have.

If rules are followed, then everything should be fine.