Go Lang，Postgres：扫描后无法获取oid

Question

I have 2 columns if table accounts:

oid and balance

By the next code I try to extract oid then balance:

// variable `id` comes from an another part

sqlstr := `SELECT * ` +
    `FROM accounts ` +
    `WHERE oid=` + id + `;`

q, err := db.Query(sqlstr)

if err != nil {
    fmt.Println("Error: GetAccount 
", err)
    return Account{}, err
}
defer q.Close()


var _id string
var bal float64

q.Next()
q.Scan(&_id)
fmt.Println("_id ", _id)


q.Next()
q.Scan(&bal)
fmt.Println("bal ", bal)

After the first q.Next() I expected to extract oid and after the second to extract balance.

But every time after the first q.Next() and after the second I only get balance.

I tried to change sqlstr to the next:

sqlstr := `SELECT oid, balance ` +
    `FROM accounts ` +
    `WHERE oid=` + id + `;`

But I still cannot extract oid.

Answer 1

Try this q.Scan(&_id, &bal), func (*Row) Scan has this signature:

func (r *Row) Scan(dest ...interface{}) error

It expects the the pointers to the values where it will store the queried data.

If you are only querying for a single row, there is func (*DB) QueryRow(). Then your code will simplify to

row := db.QueryRow(sqlstr)
err := row.Scan(&_id, &bal)
// err will be sql.ErrNoRows if no rows have been selected