sqlx structscan join query(SQLX结构扫描连接查询)

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英文:

sqlx structscan join query

问题

我是你的中文翻译助手,以下是你提供的代码的翻译:

我对Go和sqlx都不太熟悉,我想知道是否可以在一个查询中使用结构体扫描(strutscan)来处理主-从连接(master -> detail join)的情况。一个病人有多个病例,所以我想查询所有病人,并在每个病人结构体中嵌入一个Episode数组。

类似这样的代码:

type Episode struct {
    EpisodeID int    `db:"episode_id"`
    PatientID int    `db:"patient_id"`
    Status    string `db:"status"`
}

type Patient struct {
    PatientID    int            `db:"patient_id"`
    FirstName    string         `db:"first_name"`
    MiddleName   sql.NullString `db:"middle_name"`
    LastName     string         `db:"last_name"`
    Episodes     []Episode
}

query := `SELECT 
mr_patients.patient_id, 
mr_patients.first_name, 
mr_patients.middle_name, 
mr_patients.last_name, 
mr_episode_statuses.status, 
mr_episodes.episode_id, 
mr_episodes.created_at 
FROM mr_patients 
INNER JOIN mr_episodes ON mr_patients.patient_id = mr_episodes.patient_id 
INNER JOIN mr_episode_statuses ON mr_episodes.status_id = mr_episode_statuses.status_id
ORDER BY mr_patients.patient_id, mr_episodes.episode_id`

rows, err := db.Queryx(query)

if err != nil {
    log.Fatal(err)
}

var patients []Patient

for rows.Next() {
    var p Patient
    err = rows.StructScan(&p)
    if err != nil {
        log.Fatalln(err)
    } else {
        patients = append(patients, p)
    }
}

希望对你有帮助。

英文:

I'm new to go and sqlx and I would want to know if its posible to strutscan a master -> detail join clause in one query. A patient has many episodes so I want to query all patients and embed an Episode array in each Patient struct

Something like this:

type Episode struct {
		EpisodeID int    `db:"episode_id"`
		PatientID int    `db:"patient_id"`
		Status    string `db:"status"`
	}

	type Patient struct {
		PatientID    int            `db:"patient_id"`
		FirstName    string         `db:"first_name"`
		MiddleName   sql.NullString `db:"middle_name"`
		LastName     string         `db:"last_name"`
		Episodes     []Episode
	}

	query := `SELECT 
	mr_patients.patient_id, 
	mr_patients.first_name, 
	mr_patients.middle_name, 
	mr_patients.last_name, 
	mr_episode_statuses.status, 
	mr_episodes.episode_id, 
	mr_episodes.created_at 
	FROM mr_patients 
	INNER JOIN mr_episodes ON mr_patients.patient_id = mr_episodes.patient_id 
	INNER JOIN mr_episode_statuses ON mr_episodes.status_id = mr_episode_statuses.status_id
	ORDER BY mr_patients.patient_id, mr_episodes.episode_id`

	rows, err := db.Queryx(query)

	if err != nil {
		log.Fatal(err)
	}

	var patients []Patient

	for rows.Next() {
		var p Patient
		err = rows.StructScan(&p)
		if err != nil {
			log.Fatalln(err)
		} else {
			patients = append(patients, p)
		}
	}

Thanks.

答案1

得分: 2

这不会起作用,因为database/sqlsqlx不是对象关系映射器(ORM),它们不知道如何“填充”你的[]Episodes类型。sqlx可以使用“structName.fieldName”语法将单个结构字段分配给父结构,但仅限于此。它不能获取所有行,知道哪个是哪个,并将所有的Episodes正确分配给Patient。你需要一个ORM来实现这个。

英文:

It's not going to work since database/sql or sqlx aren't object relational mappers and don't know how to "populate" your type []Episodes. sqlx can assign single struct fields within a parent struct with the "structName.fieldName" syntax but that's it. It can't take all your rows, know what is what and assign all Episodes to the correct Patient. You need an ORM for that.

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  • 本文由 发表于 2016年9月28日 14:36:07
  • 转载请务必保留本文链接:https://go.coder-hub.com/39739710.html
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