code: func PgConstraintByOid(db XODB, oid pgtypes.Oid) (*PgConstraint, error) {
  	var err error
  
  	// sql query
  	const sqlstr = `SELECT ` +
  		`tableoid, cmax, xmax, cmin, xmin, oid, ctid, conname, connamespace, contype, condeferrable, condeferred, convalidated, conrelid, contypid, conindid, confrelid, confupdtype, confdeltype, confmatchtype, conislocal, coninhcount, connoinherit, conkey, confkey, conpfeqop, conppeqop, conffeqop, conexclop, conbin, consrc ` +
  		`FROM pg_catalog.pg_constraint ` +
  		`WHERE oid = $1`
  
  	// run query
  	XOLog(sqlstr, oid)
  	pc := PgConstraint{}
  
  	err = db.QueryRow(sqlstr, oid).Scan(&pc.Tableoid, &pc.Cmax, &pc.Xmax, &pc.Cmin, &pc.Xmin, &pc.Oid, &pc.Ctid, &pc.Conname, &pc.Connamespace, &pc.Contype, &pc.Condeferrable, &pc.Condeferred, &pc.Convalidated, &pc.Conrelid, &pc.Contypid, &pc.Conindid, &pc.Confrelid, &pc.Confupdtype, &pc.Confdeltype, &pc.Confmatchtype, &pc.Conislocal, &pc.Coninhcount, &pc.Connoinherit, &pc.Conkey, &pc.Confkey, &pc.Conpfeqop, &pc.Conppeqop, &pc.Conffeqop, &pc.Conexclop, &pc.Conbin, &pc.Consrc)
  	if err != nil {
  		return nil, err
  	}
  
  	return &pc, nil
  }
docs: // PgConstraintByOid retrieves a row from 'pg_catalog.pg_constraint' as a PgConstraint.
  //
  // Generated from index 'pg_constraint_oid_index'.