Task: Run a SQL query on Postgres

n8n workflow JSON:
{"nodes":[{"name":"On clicking 'execute'","type":"n8n-nodes-base.manualTrigger","position":[250,300],"parameters":{},"typeVersion":1},{"name":"Postgres","type":"n8n-nodes-base.postgres","position":[450,300],"parameters":{"query":"SELECT * from sometable;","operation":"executeQuery"},"credentials":{"postgres":"postgres-creds"},"typeVersion":1}],"connections":{"On clicking 'execute'":{"main":[[{"node":"Postgres","type":"main","index":0}]]}}}