postgres_exporter:Failed to create PostgresCollector

I have a question here. When I execute postgres_exporter on the monitoring node, an error is reported.
The following is the error log:

[root@ocbc postgres_exporter]# ./postgres_exporter
ts=2022-09-05T10:07:13.883Z caller=main.go:124 level=error msg=“Failed to create PostgresCollector” err=“malformed dsn ""”

Here someone tell me why,please! :pray: