Support connect to both tls and non-tls server (#174)

- Using tls=preferred, the server accepts a TLS connection from the client but is also okay if the client does not switch to encryption.
- upgrade go-sql-driver > 1.7.0 to use this feature for older version MySQL server go-sql-driver/mysql#1370.

cmd/go-tpc/main.go

@@ -98,7 +98,7 @@ func newDB(targets []string, driver string, user string, password string, dbName
 		switch driver {
 		case mysqlDriver:
 			// allow multiple statements in one query to allow q15 on the TPC-H
-			dsn := fmt.Sprintf("%s:%s@tcp(%s)/%s?multiStatements=true", user, password, addr, dbName)
+			dsn := fmt.Sprintf("%s:%s@tcp(%s)/%s?multiStatements=true&tls=preferred", user, password, addr, dbName)
 			if len(connParams) > 0 {
 				dsn = dsn + "&" + connParams
 			}

go.mod

@@ -4,7 +4,7 @@ go 1.21
 
 require (
 	github.com/HdrHistogram/hdrhistogram-go v1.0.0
-	github.com/go-sql-driver/mysql v1.5.0
+	github.com/go-sql-driver/mysql v1.7.1
 	github.com/jedib0t/go-pretty v4.3.0+incompatible
 	github.com/lib/pq v1.10.6
 	github.com/olekukonko/tablewriter v0.0.5

go.sum

@@ -73,8 +73,9 @@ github.com/go-openapi/errors v0.19.8/go.mod h1:cM//ZKUKyO06HSwqAelJ5NsEMMcpa6VpX
 github.com/go-openapi/strfmt v0.19.11 h1:0+YvbNh05rmBkgztd6zHp4OCFn7Mtu30bn46NQo2ZRw=
 github.com/go-openapi/strfmt v0.19.11/go.mod h1:UukAYgTaQfqJuAFlNxxMWNvMYiwiXtLsF2VwmoFtbtc=
 github.com/go-sql-driver/mysql v1.4.0/go.mod h1:zAC/RDZ24gD3HViQzih4MyKcchzm+sOG5ZlKdlhCg5w=
-github.com/go-sql-driver/mysql v1.5.0 h1:ozyZYNQW3x3HtqT1jira07DN2PArx2v7/mN66gGcHOs=
 github.com/go-sql-driver/mysql v1.5.0/go.mod h1:DCzpHaOWr8IXmIStZouvnhqoel9Qv2LBy8hT2VhHyBg=
+github.com/go-sql-driver/mysql v1.7.1 h1:lUIinVbN1DY0xBg0eMOzmmtGoHwWBbvnWubQUrtU8EI=
+github.com/go-sql-driver/mysql v1.7.1/go.mod h1:OXbVy3sEdcQ2Doequ6Z5BW6fXNQTmx+9S1MCJN5yJMI=
 github.com/go-stack/stack v1.8.0 h1:5SgMzNM5HxrEjV0ww2lTmX6E2Izsfxas4+YHWRs3Lsk=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/go-toolsmith/astcast v1.0.0/go.mod h1:mt2OdQTeAQcY4DQgPSArJjHCcOwlX+Wl/kwN+LbLGQ4=