Client APIs
Example
```c
duckdb_database db;
duckdb_connection con;

if (duckdb_open(NULL, &db) == DuckDBError) {
// handle error
}
if (duckdb_connect(db, &con) == DuckDBError) {
// handle error
}

// run queries...

// cleanup
duckdb_disconnect(&con);
duckdb_close(&db);
```