duanquan1207 2018-11-12 16:34
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Go Lang,Postgres:扫描后无法获取oid

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.

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1条回答 默认 最新

  • dongll0502 2018-11-12 17:16
    关注

    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
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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