:sig
MySQL* mysql_connect(String host = "localhost", String username = "root", String password = "", String database = "")

:params
host : host name of the MySQL server
username : user name
password : password
database : optional initial database name
return value : pointer to the MySQL connection struct

:see
>mysql

:content
Establishes a connection to a MySQL server and returns a request-owned pointer to the connection struct. When `database` is non-empty, the server selects it as part of connection establishment and restores it after every cross-request connection reset. A failed connection also returns a wrapper so that `mysql_error()` can report the failure; use `mysql_connected()` before issuing optional work that requires a live server handle.

This connection handle is then used with helpers such as `mysql_query()`, `mysql_error()`, and `mysql_disconnect()`.

MySQL handles are request-scoped framework resources. Repeated `mysql_connect()` calls with the same host, credentials, and database reuse one server connection within the current request. Database identity is part of both request-local and worker-persistent pool keys. Each call creates a lease and `mysql_disconnect()` releases that lease. At request cleanup UCE returns the server connection to the current worker's persistent pool, then resets it before cross-request reuse. The pool holds up to `MYSQL_PERSISTENT_POOL_SIZE` connections per worker (default 8); set the size to 0 to disable cross-request reuse. `MYSQL_PERSISTENT_POOL_IDLE_TIMEOUT_SECONDS` retires idle entries at the first later request boundary (default 300, 0 keeps unlimited idle retention). A completely idle worker has no boundary and does not proactively close sockets. Never store a `MySQL*` in globals, sessions, or other state that can outlive the current request.

:example
MySQL* db = mysql_connect();
print(mysql_connected(db) ? "connected to MySQL" : "no MySQL server reachable with these credentials", "\n");
if(db != 0) mysql_disconnect(db);