sql - Go SQL扫描的行被覆盖

Question

我正在尝试从 SQL 服务器上的表中读取所有行，并将它们存储在字符串 slice 中以备后用。我遇到的问题是每次扫描新行时以前扫描的行都会被覆盖，即使我已经将所有可变字节 slice 转换为不可变字符串并将结果 slice 保存到另一个 slice 。这是我正在使用的代码:

rawResult := make([]interface{}, len(cols)) // holds anything that could be in a row
result := make([]string, len(cols)) // will hold all row elements as strings
var results [][]string // will hold all the result string slices
dest := make([]interface{}, len(cols)) // temporary, to pass into scan
for i, _ := range rawResult {
    dest[i] = &rawResult[i] // fill dest with pointers to rawResult to pass into scan
}
for rows.Next() { // for each row
    err = rows.Scan(dest...) // scan the row
    if err != nil {
        log.Fatal("Failed to scan row", err)
    }
    for i, raw := range rawResult { // for each scanned byte slice in a row
        switch rawtype := raw.(type){ // determine type, convert to string
        case int64:
            result[i] = strconv.FormatInt(raw.(int64), 10)
        case float64:
            result[i] = strconv.FormatFloat(raw.(float64), 'f', -1, 64)
        case bool:
            result[i] = strconv.FormatBool(raw.(bool))
        case []byte:
            result[i] = string(raw.([]byte))
        case string:
            result[i] = raw.(string)
        case time.Time:
            result[i] = raw.(time.Time).String()
        case nil:
            result[i] = ""
        default: // shouldn't actually be reachable since all types have been covered
            log.Fatal("Unexpected type %T", rawtype)
        }
    }
    results = append(results, result) // append the result to our slice of results
}

我确信这与 Go 处理变量和内存的方式有关，但我似乎无法修复它。有人可以解释一下我不明白的地方吗？

Answer 1

您应该为每个数据行创建新 slice 。请注意，一个 slice 有一个指向底层数组的指针，因此您添加到 results 中的每个 slice 在实际数据数组上都有相同的指针。这就是您遇到这种行为的原因。