未选择Golang MySQL数据库

Question

I'm using github.com/go-sql-driver/mysql package to connect to MySQL. It works well except when I select a database (USE), I can't run queries against it.

package main

import (
    "database/sql"
    "fmt"
    "log"
)

import _ "github.com/go-sql-driver/mysql"

func main() {
    dsn := "root:@/"
    db, err := sql.Open("mysql", dsn)
    if err != nil {
        fmt.Println("Failed to prepare connection to database. DSN:", dsn)
        log.Fatal("Error:", err.Error())
    }

    err = db.Ping()
    if err != nil {
        fmt.Println("Failed to establish connection to database. DSN:", dsn)
        log.Fatal("Error:", err.Error())
    }

    _, err = db.Query("USE test")
    if err != nil {
        fmt.Println("Failed to change database.")
        log.Fatal("Error:", err.Error())
    }

    _, err = db.Query("SHOW TABLES")
    if err != nil {
        fmt.Println("Failed to execute query.")
        log.Fatal("Error:", err.Error())
    }
}

The program produces this output:

Error 1046: No database selected

Answer 1

Specify the database directly in the DSN (Data Source Name) part of the sql.Open function:

dsn := "user:password@/dbname"
db, err := sql.Open("mysql", dsn)