How to insert multiple data at once

why not something like this? (writing here without testing so there might be syntax errors):

sqlStr := "INSERT INTO test(n1, n2, n3) VALUES "
vals := []interface{}{}

for _, row := range data {
    sqlStr += "(?, ?, ?),"
    vals = append(vals, row["v1"], row["v2"], row["v3"])
}
//trim the last ,
sqlStr = sqlStr[0:len(sqlStr)-1]
//prepare the statement
stmt, _ := db.Prepare(sqlStr)

//format all vals at once
res, _ := stmt.Exec(vals...)