Setting charset=utf8mb4,utf8 does not work (connection error)

[matwachich]

The comma will get escaped in the DSN, and the connexion to the server will fail.
Tested with latest 1.9.3 and MariaDB 11.8

[methane]

I can not reproduce.

package main

import (
	"fmt"

	"database/sql"

	"github.com/go-sql-driver/mysql"
)

func main() {
	dsn := "root@/?charset=utf8mb4,utf8"
	cfg, err := mysql.ParseDSN(dsn)
	if err != nil {
		panic(err)
	}

	fmt.Printf("formatted dsn: %s\n", cfg.FormatDSN())

	db, err := sql.Open("mysql", dsn)
	if err != nil {
		panic(err)
	}
	defer db.Close()
	err = db.Ping()
	if err != nil {
		panic(err)
	}

	var val string
	err = db.QueryRow("SELECT @@character_set_client").Scan(&val)
	if err != nil {
		panic(err)
	}
	fmt.Printf("character_set_client=%s\n", val)
}

formatted dsn: root@tcp(127.0.0.1:3306)/?charset=utf8mb5,utf8
character_set_client=utf8mb3

[matwachich]

I build my dsn by manually populating a Config struct Le sam. 21 juin 2025 à 13:08, Inada Naoki ***@***.***> a écrit :

…

*methane* left a comment (go-sql-driver/mysql#1729) <#1729 (comment)> I can not reproduce. package main import ( "fmt" "database/sql" "github.com/go-sql-driver/mysql" ) func main() { dsn := "root@/?charset=utf8mb4,utf8" cfg, err := mysql.ParseDSN(dsn) if err != nil { panic(err) } fmt.Printf("formatted dsn: %s\n", cfg.FormatDSN()) db, err := sql.Open("mysql", dsn) if err != nil { panic(err) } defer db.Close() err = db.Ping() if err != nil { panic(err) } var val string err = db.QueryRow("SELECT @@character_set_client").Scan(&val) if err != nil { panic(err) } fmt.Printf("character_set_client=%s\n", val) } formatted dsn: ***@***.***(127.0.0.1:3306)/?charset=utf8mb5,utf8 character_set_client=utf8mb3 — Reply to this email directly, view it on GitHub <#1729 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AANVJ7VLCSEFP4YDKFZFSV33EVDK3AVCNFSM6AAAAAB7YXMUO2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDSOJTGU2DONZZGI> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[methane]

it is not supported. multiple charset is legacy feature, not recommended.