将数据保存到文件中的Golang SQL查询。

huangapple
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英文:

Saving data to a file golang sql query

问题

帮助我，如何将接收到的数据写入文件？我需要将section_id和modified_by的所有数据写入文件。

  1. rows, err := db.Query("select section_id, modified_by from enrollment where rownum < 5")
  2. if err != nil {
  3.     fmt.Println("Error running query")
  4.     fmt.Println(err)
  5.     return
  6. }
  7. defer rows.Close()
  9. var section_id string
  10. var modified_by string
  11. for cont := true; cont; cont = rows.NextResultSet() {
  12.     for rows.Next() {
  13.         err := rows.Scan(&section_id, &modified_by)
  14.         if err != nil {
  15.             fmt.Println(err)
  16.         }
  17.         fmt.Println(section_id, modified_by)
  18.         // 在这里将数据写入文件
  19.     }
  20. }

谢谢您的帮助！

英文:

Help me, pls. How can I write the received data on file? I need write all-data from section_id, modified_by.

  1. rows, err := db.Query(&quot;select section_id, modified_by from enrollment where rownum &lt; 5&quot;)
  2. 	if err != nil {
  3. 		fmt.Println(&quot;Error running query&quot;)
  4. 		fmt.Println(err)
  5. 		return
  6. 	}
  7. 	defer rows.Close()
  9. 	var section_id string
  10. 	var modified_by string
  11. 	for cont := true; cont; cont = rows.NextResultSet() {
  12. 		for rows.Next() {
  13. 			err := rows.Scan(&amp;section_id, &amp;modified_by)
  14. 			if err != nil {
  15. 				fmt.Println(err)
  16. 			}
  17. 			fmt.Println(section_id, modified_by)
  18. 		}
  19. 	}
  21. }

Thank you for any help!

答案1

得分: 0

用以下代码替换循环部分：

  1. f, err := os.Create("data.txt")
  2. if err != nil {
  3.     log.Fatalf("无法打开文件：%v", err)
  4. }
  5. defer f.Close()
  7. for cont := true; cont; cont = rows.NextResultSet() {
  8.     for rows.Next() {
  9.         err := rows.Scan(&section_id, &modified_by)
  10.         if err != nil {
  11.             fmt.Println(err)
  12.         }
  13.         fmt.Println(section_id, modified_by)
  14.         n, err := f.WriteString(fmt.Sprintf("%s 修改了 %d", modified_by, section_id))
  15.         if err != nil {
  16.             log.Fatalf("无法写入文件：%v", err)
  17.         }
  18.         log.Printf("写入了 %d 字节\n", n)
  19.     }
  20. }

首先打开一个文件，并检查是否有错误，然后在循环中再次将每一行写入文件，并在其中进行错误检查。更多示例请参见这里。

英文:

Replace the loop with

  1. f, err := os.Create(&quot;data.txt&quot;)
  2. if err != nil {
  3.     log.Fatalf(&quot;could not open file: %v&quot;, err)
  4. }
  5. defer f.Close()
  7. for cont := true; cont; cont = rows.NextResultSet() {
  8.     for rows.Next() {
  9.         err := rows.Scan(&amp;section_id, &amp;modified_by)
  10.         if err != nil {
  11.             fmt.Println(err)
  12.         }
  13.         fmt.Println(section_id, modified_by)
  14.         n, err := f.WriteString(fmt.Sprintf(&quot;%s modified %d&quot;, modified_by, section_id))
  15.         if err != nil {
  16.             log.Fatalf(&quot;could not write to file: %v&quot;, err)
  17.         }
  18.         log.Printf(&quot;Wrote %d bytes\n&quot;, n)
  19.     }
  20. }

You first open a file, check for errors and then in the loop write every row to the file again with error checks in between. See here for more examples.

答案2

得分: 0

你可以使用json.MarshalIndent将数据保存为格式化的json文件。

  1. package main
  3. import (
  4. 	"encoding/json"
  5. 	"fmt"
  6. 	"io/ioutil"
  7. )
  9. func ToJsonFile(path string, v interface{}) {
  10. 	bytes, _ := json.MarshalIndent(v, "", " ")
  12. 	if err := ioutil.WriteFile(path, bytes, 0644); err != nil {
  13. 		fmt.Println(err)
  14. 		panic(err)
  15. 	}
  16. 	fmt.Println("已将数据保存为json文件，路径为：" + path)
  17. }
  19. type Enrollment struct {
  20. 	SectionId  string `json:"section_id"`
  21. 	ModifiedBy string `json:"modified_by"`
  22. }
  24. func PersistData() error {
  25. 	// 在这里实现数据库操作...
  27. 	// 用于存放数据的数组
  28. 	var data []*Enrollment
  30. 	rows, err := db.Query("select section_id, modified_by from enrollment where rownum < 5")
  31. 	if err != nil {
  32. 		fmt.Println("运行查询时出错")
  33. 		fmt.Println(err)
  34. 		return err
  35. 	}
  36. 	defer rows.Close()
  38. 	for cont := true; cont; cont = rows.NextResultSet() {
  39. 		for rows.Next() {
  40. 			document := &Enrollment{}
  42. 			err := rows.Scan(&document.SectionId, &document.ModifiedBy)
  43. 			if err != nil {
  44. 				fmt.Println(err)
  45. 				return err
  46. 			}
  47. 			data = append(data, document)
  48. 			fmt.Println(document.SectionId, document.ModifiedBy)
  49. 		}
  50. 	}
  52. 	// 将数据持久化为json文件
  53. 	ToJsonFile("DATA.json", data)
  55. 	return nil
  56. }

以上是要翻译的内容。

英文:

You can save your data as a beautified json file using json.MarshalIndent.

  1. package main
  2. import (
  3. &quot;encoding/json&quot;
  4. &quot;fmt&quot;
  5. &quot;io/ioutil&quot;
  6. )
  7. func ToJsonFile(path string, v interface{}) {
  8. bytes, _ := json.MarshalIndent(v, &quot;&quot;, &quot; &quot;)
  9. if err := ioutil.WriteFile(path, bytes, 0644); err != nil {
  10. fmt.Println(err)
  11. panic(err)
  12. }
  13. fmt.Println(&quot;Saved the data as json file at &quot; + path)
  14. }
  15. type Enrollment struct {
  16. SectionId  string `json:&quot;section_id&quot;`
  17. ModifiedBy string `json:&quot;modified_by&quot;`
  18. }
  19. func PersistData() error {
  20. // implement db here ...
  21. // array to put data together
  22. var data []*Enrollment
  23. rows, err := db.Query(&quot;select section_id, modified_by from enrollment where rownum &lt; 5&quot;)
  24. if err != nil {
  25. fmt.Println(&quot;Error running query&quot;)
  26. fmt.Println(err)
  27. return err
  28. }
  29. defer rows.Close()
  30. for cont := true; cont; cont = rows.NextResultSet() {
  31. for rows.Next() {
  32. document := &amp;Enrollment{}
  33. err := rows.Scan(&amp;document.SectionId, &amp;document.ModifiedBy)
  34. if err != nil {
  35. fmt.Println(err)
  36. return err
  37. }
  38. data = append(data, document)
  39. fmt.Println(document.SectionId, document.ModifiedBy)
  40. }
  41. }
  42. // persist data to a json file
  43. ToJsonFile(&quot;DATA.json&quot;, data)
  44. return nil
  45. }

huangapple
  • 本文由 发表于 2022年8月26日 21:45:10
  • 转载请务必保留本文链接：https://go.coder-hub.com/73502000.html
  • database
  • go
  • sql
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