Seperate database connection function from the query function - mysql

Question

I have been trying to execute queries with http://www.github.com/go-sql-driver/mysql and have been following this tutorial: https://tutorialedge.net/golang/golang-mysql-tutorial/
Now this tutorial does everything in 1 custom function, but I've tried to split up opening the database connection and the queries itself in seperate functions. The way I've done this is like this:
package main
import (
"fmt"
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
type SqlResult struct {
id int
}
var db *sql.DB
func main() {
dbConnection:= openDatabaseConnection();
getID(dbConnection);
}
func openDatabaseConnection() *sql.DB {
db,err:= sql.Open("mysql","username:password#tcp(127.0.0.1:3306)/test");
if err != nil {
panic(err.Error())
}
defer db.Close()
return db
}
func getID(db *sql.Db) {
results,err:= db.Query("SELECT id FROM test")
for results.Next() {
var result SqlResult
err=results.Scan(&result.id)
if err != nil {
panic(err.Error())
}
fmt.Print(result.id)
}
}
This doesn't print out anything but also doesn't give an error.
Now when I put my code in 1 function, like this:
package main
import (
"fmt"
"database/sql"
_ "github.com/go-sql-driver/mysql"
)
type SqlResult struct {
id int
}
var db *sql.DB
func main() {
openDatabaseConnection();
}
func openDatabaseConnection() *sql.DB {
db,err:= sql.Open("mysql","username:password#tcp(127.0.0.1:3306)/test");
if err != nil {
panic(err.Error())
}
results,err:= db.Query("SELECT id FROM test")
for results.Next() {
var result SqlResult
err=results.Scan(&result.id)
if err != nil {
panic(err.Error())
}
fmt.Print(result.id)
}
defer db.Close()
return db
}
This returns me all the id's, but I want to split the functionality up. It doesn't seem like opening the database connection everytime I need a new query is the right solution.
Does anyone know what I'm doing wrong in my first example and if so, what would be the right way of the way I want it to be?

Answer 1

"what would be the right way of the way I want it to be?"
package main
import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
)
var db *sql.DB
func main() {
db = openDatabaseConnection()
defer db.Close()
printIds(db)
}
func openDatabaseConnection() *sql.DB {
db, err := sql.Open("mysql", "username:password#tcp(127.0.0.1:3306)/test")
if err != nil {
panic(err)
} else if err := db.Ping(); err != nil {
panic(err)
}
return db
}
func printIds(db *sql.DB) {
rows, err := db.Query("SELECT id FROM test")
if err != nil {
panic(err)
}
defer rows.Close()
for rows.Next() {
var id int
if err := rows.Scan(&id); err != nil {
panic(err)
}
fmt.Println(id)
}
if err := rows.Err(); err != nil {
panic(err)
}
}