恐慌：sql：预期0参数，得到1

Question

I am trying to execute queries with Go, but I cannot manage to request any query, because it keeps giving me the same error over and over.

I have changed the query multiple times, but that doesn't seem to help. Also i have changed QueryRow in Query, unfortunately that doesn't help either.

func test123() {

    db, err := sql.Open("mysql", "root:password@tcp(127.0.0.1:3306)/vitaintellectdb")
    if err != nil {
        panic(err.Error())
    }

    id := 1
    var col string
    sqlStatement := `SELECT naam FROM medewerker WHERE naam="jansen"`
    row := db.QueryRow(sqlStatement, id)
    err2 := row.Scan(&col)
    if err2 != nil {
        if err2 == sql.ErrNoRows {
            fmt.Println("Zero rows found")
        } else {
            panic(err2)
        }
    }

}

QueryRow is designed to give you 1 row in return. Unfortunately the error is telling me that there should be no returns, I expect 1 row in return.

Answer 1

sqlStatement := `SELECT naam FROM medewerker WHERE naam="jansen"`
row := db.QueryRow(sqlStatement, id)

The given sql statement has no parameter. The following sql statement including the placeholder might work better.

sqlStatement := `SELECT naam FROM medewerker WHERE medewerkernummer =?`
row := db.QueryRow(sqlStatement, id)

Depending how your id-column is named you might have to change naam=? to idColumn=?. In the examples here you might find inspiration.