Transfer succeeds with negative balance

Code reviewDatabases & SQLReliability & on-callSenior–Staff~22 min

Review this Go funds-transfer. It opens a transaction, debits, validates, then credits.

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1func transfer(db *sql.DB, from, to string, amt int) error {

2 tx, _ := db.Begin()

3 tx.Exec("UPDATE acct SET bal = bal - $1 WHERE id = $2", amt, from)

4 var bal int

5 tx.QueryRow("SELECT bal FROM acct WHERE id = $1", from).Scan(&bal)

6 if bal < 0 {

7 return errors.New("insufficient funds")

8 }

9 tx.Exec("UPDATE acct SET bal = bal + $1 WHERE id = $2", amt, to)

10 return tx.Commit()

11}

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