【转载】记Golang数据库查询封装的坑

func openDbString(sqlstring string) string {
    conn := openDb()
    defer conn.Close()
    stmt, err := conn.Prepare(sqlstring)
    if err != nil {
        fmt.Println("Query Error", err)
        return "Error"
    }
    defer stmt.Close()
    rows, err := stmt.Query()
    if err != nil {
        fmt.Println("Query Error", err)
        return "Error"
    }
    defer rows.Close()
    // Get column names
    columns, err := rows.Columns()
    if err != nil {
        panic(err.Error()) // proper error handling instead of panic in your app
    }
    // Make a slice for the values
    values := make([]sql.RawBytes, len(columns))
    // rows.Scan wants '[]interface{}' as an argument, so we must copy the
    // references into such a slice
    // See http://code.google.com/p/go-wiki/wiki/InterfaceSlice for details
    scanArgs := make([]interface{}, len(values))
    for i := range values {
        scanArgs[i] = &values[i]
    }
    // Fetch rows
    var jsonstring string
    jsonstring = "{\"timestamp\": \"" + time.Now().Format("2006-01-02 15:04:05") + "\",\"data\":["
    allcount := 0
    for rows.Next() {
        jsonstring += "{"
        // get RawBytes from data
        err = rows.Scan(scanArgs...)
        if err != nil {
            panic(err.Error()) // proper error handling instead of panic in your app
        }
        // Now do something with the data.
        // Here we just print each column as a string.
        var value string
        for i, col := range values {
            // Here we can check if the value is nil (NULL value)
            if col == nil {
                value = "NULL"
            } else {
                value = string(col)
            }
            //          fmt.Println(columns[i], ": ", value)
            if i == len(values)-1 {
                jsonstring += "\"" + columns[i] + "\":\"" + value + "\""
            } else {
                jsonstring += "\"" + columns[i] + "\":\"" + value + "\","
            }
            //          fmt.Println(" :", i, ": ", col, len(values))
        }
        //fmt.Println("replace before :", jsonstring, ": ", len(jsonstring))
        //jsonstring = strings.Replace(jsonstring, ",", " ", len(jsonstring))
        //fmt.Println("replace after :", jsonstring, ": ", len(jsonstring))
        //      fmt.Println("-----------------------------------", allcount)
        jsonstring += "},"
        allcount++
    }
    if allcount > 0 {
        jsonstring = Substr(jsonstring, 0, len(jsonstring)-1)
    }
    jsonstring += "]}"
    if err = rows.Err(); err != nil {
        panic(err.Error()) // proper error handling instead of panic in your app
    }
    return jsonstring
}