db.go

   // In main part of the application
  db, err := sql.Open("postgres", connectString)
	defer db.Close()
	checkErr(err)

  // In single request
  
	tx, err := db.BeginTx(context.TODO(), TxOptions{sql.LevelRepeatableRead}) // Gets a single connection from pool and start transaction
	checkErr(err)
  
  rows, err := tx.Query(sql1) // Run query in that transaction
  checkErr(err)
  doStuffWith(rows)
  
  tx.Query(sql2)
  checkErr(err)
  doStuffWith(rows)
  
  tx.Commit()