在golang中显示数据库的结果

huangapple
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英文:

Displaying results from a database in golang

问题

我正在从一个表单中读取一个MySQL查询输入：

  1. <h1>MySQL页面</h1>
  2. <small>在这里执行查询和编辑数据库</small>
  3. <form method="get" action="">
  4.   <label for="sqlQuery">MySQL查询：</label>
  5.   <input type="text" id="sqlQuery" name="sqlQuery">
  6.   <button type="submit">执行查询</button>
  7. </form>

之后，我想使用GoLang在同一页上显示结果，但它一直告诉我：

  1. # command-line-arguments
  2. ./sql.go:128: 无法将结果（类型为sql.Result）转换为字符串类型

请记住，这是我写的第一个GoLang应用程序，如果这是一个简单的问题，我很抱歉，以下是GoLang代码：

  1. func sqlQueryHandler(response http.ResponseWriter, request *http.Request){
  2.   userName := getUserName(request)
  3.   db, err := sql.Open("mysql", userName)
  4.   fmt.Fprintf(response, sqlPage)
  5.   sqlCommand := request.FormValue("sqlQuery")
  6.   //fmt.Fprintf(response, sqlCommand)
  7.   if err != nil {
  8.     fmt.Fprintf(response, "\n\n在执行MySQL命令时发生错误：%s", err)
  9.     panic(err)
  10.   } else {
  11.     data, err := db.Exec(sqlCommand)
  12.     if err != nil {
  13.       http.Redirect(response, request, "/error", 302)
  14.     } else {
  15.       // 在这里显示SQL查询的输出
  16.     }
  17.   }
  18. }
英文:

I'm reading a MySQL query input from a form:

  1. &lt;h1&gt;MySQL Page&lt;/h1&gt;
  2. &lt;small&gt;Perform queries and edit the database from here&lt;/small&gt;
  3. &lt;form method=&quot;get&quot; action=&quot;&quot;&gt;
  4.   &lt;label for=&quot;sqlQuery&quot;&gt;MySQL Query:&lt;/label&gt;
  5.   &lt;input type=&quot;text&quot; id=&quot;sqlQuery&quot; name=&quot;sqlQuery&quot;&gt;
  6.   &lt;button type=&quot;submit&quot;&gt;Perform Query&lt;/button&gt;
  7. &lt;/form&gt;

After that I want to display the results on the same page using GoLang, however it keeps telling me that:

  1. # command-line-arguments
  2. ./sql.go:128: cannot convert results (type sql.Result) to type string

Please keep in mind, this is the first golang app I've ever written so I apologize if this is a simple issue, here is the golang code:

  1. func sqlQueryHandler(response http.ResponseWriter, request *http.Request){
  2.   userName := getUserName(request)
  3.   db, err := sql.Open(&quot;mysql&quot;, userName)
  4.   fmt.Fprintf(response, sqlPage)
  5.   sqlCommand := request.FormValue(&quot;sqlQuery&quot;)
  6.   //fmt.Fprintf(response, sqlCommand)
  7.   if err != nil {
  8.     fmt.Fprintf(response, &quot;\n\nAn error occured during your MySQL command: %s&quot;, err)
  9.     panic(err)
  10.   } else {
  11.     data, err := db.Exec(sqlCommand)
  12.     if err != nil {
  13.       http.Redirect(response, request, &quot;/error&quot;, 302)
  14.     } else {
  15.       // display the output of the sql query here
  16.     }
  17.   }
  18. }

答案1

得分: 2

根据你的代码，这里有一个示例：

  1. func sqlQueryHandler(response http.ResponseWriter, request *http.Request) {
  2.     var (
  3.         userName   = getUserName(request)
  4.         sqlCommand = request.FormValue("sqlQuery")
  5.     )
  7.     db, err := sql.Open("mysql", userName)
  8.     if err != nil {
  9.         fmt.Fprintf(response, "\n\n在执行MySQL命令时发生错误：%s", err)
  10.         // 如果发生错误，你可以在这里停止执行，不需要else语句
  11.         panic(err)
  12.     }
  13.     rows, err := db.Query(sqlCommand)
  14.     if err != nil {
  15.         http.Redirect(response, request, "/error", 302)
  16.         // 返回，所以不需要else语句
  17.         return
  18.     }
  20.     if err != nil {
  21.         panic(err)
  22.     }
  23.     defer rows.Close()
  24.     for rows.Next() {
  25.         var (
  26.             name string
  27.             age  int
  28.         )
  29.         if err := rows.Scan(&name, &age); err != nil {
  30.             panic(err)
  31.         }
  32.         fmt.Printf("%s is %d\n", name, age)
  33.     }
  34.     if err := rows.Err(); err != nil {
  35.         panic(err)
  36.     }
  37. }

然而，这种方法存在几个问题：

  • 你从服务器外部传递了SQL语句。任何访问这个函数的人都可以读取你服务器上的所有数据。
  • Go语言的一个优点是它是一种强类型语言。但是在这里，你正在构建一个处理通用SQL查询的函数，这与“强类型语言”的范例相矛盾。你可以编写处理不同结构化数据的通用函数（比如json.Unmarshal()），但是特别是在编程Go语言的早期阶段，你不应该这样做。
英文:

Here an example based on your code:

  1. func sqlQueryHandler(response http.ResponseWriter, request *http.Request) {
  2. 	var (
  3. 		userName   = getUserName(request)
  4. 		sqlCommand = request.FormValue(&quot;sqlQuery&quot;)
  5. 	)
  7. 	db, err := sql.Open(&quot;mysql&quot;, userName)
  8. 	if err != nil {
  9. 		fmt.Fprintf(response, &quot;\n\nAn error occured during your MySQL command: %s&quot;, err)
  10. 		// if you panic you stop here anyway. no else needed
  11. 		panic(err)
  12. 	}
  13. 	rows, err := db.Query(sqlCommand)
  14. 	if err != nil {
  15. 		http.Redirect(response, request, &quot;/error&quot;, 302)
  16. 		// return, so no else is needed
  17. 		return
  18. 	}
  20. 	if err != nil {
  21. 		panic(err)
  22. 	}
  23. 	defer rows.Close()
  24. 	for rows.Next() {
  25. 		var (
  26. 			name string
  27. 			age  int
  28. 		)
  29. 		if err := rows.Scan(&amp;name, &amp;age); err != nil {
  30. 			panic(err)
  31. 		}
  32. 		fmt.Printf(&quot;%s is %d\n&quot;, name, age)
  33. 	}
  34. 	if err := rows.Err(); err != nil {
  35. 		panic(err)
  36. 	}
  37. }

There are several problems however with this approach:

  • You are passing the sql from outside the server. Anyone accessing this can read all the data from your server.
  • One of Go's strengths is being a typed language. Here you are building a general sql query function which contradicts the typed language paradigm. You can write general function dealing with differently structured data (like json.Unmarshal()) -- but especially early in programming go you shouldn't.

huangapple
  • 本文由 发表于 2017年8月18日 00:04:39
  • 转载请务必保留本文链接：https://go.coder-hub.com/45740042.html
  • go
  • mysql
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