Run prepare on the transaction, not the db

builtin/logical/mssql/path_creds_create.go

@@ -64,7 +64,7 @@ func (b *backend) pathCredsCreateRead(
 		return nil, err
 	}
 
-	// Get our connection
+	// Get our handle
 	db, err := b.DB(req.Storage)
 	if err != nil {
 		return nil, err
@@ -83,7 +83,7 @@ func (b *backend) pathCredsCreateRead(
 
 	// Execute each query
 	for _, query := range SplitSQL(roleSQL) {
-		stmt, err := db.Prepare(Query(query, map[string]string{
+		stmt, err := tx.Prepare(Query(query, map[string]string{
 			"name":     username,
 			"password": password,
 		}))