Else condition seems not working in go - mysql

Question

I have a MySQL database with one value in it, a string: "192.168.0.1"
Here is my code:
package main
import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
)
func checkErr(err error) {
if err != nil {
panic(err)
}
}
func main() {
db, err := sql.Open("mysql", "be:me#tcp(127.0.0.1:3306)/ipdb?charset=utf8")
checkErr(err)
ip := "'192.168.0.1'"
rows, err := db.Query("SELECT * FROM Ip_ipdata WHERE ipHost=" + ip)
fmt.Println("insert")
if rows != nil {
for rows.Next() {
var id int
var ip string
err = rows.Scan(&id, &ip)
checkErr(err)
fmt.Println(id)
fmt.Println(ip)
}
} else {
fmt.Println("insert2")
stmt, err2 := db.Prepare("INSERT Ip_ipdata SET ipHost=2")
checkErr(err2)
_, err3 := stmt.Exec(ip)
checkErr(err3)
}
fmt.Println("end")
}
When I put "'192.168.0.1'" in ip it works and shows as expected.
But when I put "'192.168.0.2'" in ip the else statement isn't run and it just exits.
It didn't print "insert2"
screenshot 1
screenshot 2

Answer 1

You should get used to using '?' placeholders in your sql to allow for proper escaping and prevent any potential SQL injection attacks.
You should always check the error in Go before using the returned value.
ip := "192.168.0.1"
rows, err := db.Query("SELECT * FROM Ip_ipdata WHERE ipHost=?", ip)
if err != nil {
// handle error
}
// this will ensure that the DB connection gets put back into the pool
defer rows.Close()
for rows.Next() {
// scan here
}

Answer 2

The Rows returned by Query will not be nil in the case of no results, it will be empty. Try something like this:
func main() {
...
fmt.Println("insert")
checkErr(err)
defer rows.Close()
var found bool
for rows.Next() {
found = true
...
}
if !found {
fmt.Println("insert2")
...
}
fmt.Println("end")
}
Note that like #jmaloney said, more robust error handling is a must as is closing your Rows pointer.