How to use csv.Writer to output MySQL data

Question

I'm trying to export the results of a MySQL query to a .csv file via Go.

In my current code, I am able to print out the results of my query in a command window, but I'd like to export those results via .csv file.

My current code looks like this:

results, err := db.Query("SELECT id, testId, testtwoId, testthreeId, testfourId  FROM TestTable LIMIT 100")
    if err != nil {
        panic(err.Error())
    }

    for results.Next() {
        var estTable TestTable

        err = results.Scan(&orderEvent.id, &orderEvent.testId, &orderEvent.eventId, &orderEvent.createTime, &orderEvent.updateTime)
        if err != nil {
            panic(err.Error())
        }
        log.Println(TestTable.id, TestTable.testId, TestTable.testtwoId, TestTable.testthreeId, TestTable.testfourId)
    }

When running my file, I am able to view my tables data without issue, but I'd still like to export this data via .csv.

I was looking around and found some code for .csv functionality, however I'm uncertain how to apply this to my current code.

I thought about applying something like this:


    file, err := os.Create("result.csv")
    checkError("Cannot create file", err)
    defer file.Close()

    writer := csv.NewWriter(file)
    defer writer.Flush()

    for _, value := range data {
        err := writer.Write(value)
        checkError("Cannot write to file", err)
    }
}

func checkError(message string, err error) {
    if err != nil {
        log.Fatal(message, err)
    }
}

However, I am currently not sure how to apply this in my code.

Why are you doing this with Go at all, when you can do it directly with MySQL? — Jonathan Hall
– Jonathan Hall, Commented Sep 18, 2019 at 16:44

Jonathan Hall · Accepted Answer · 2019-09-18 16:42:39Z

1

csv.Write in stdlib gets an array of strings, so you should do something like this in your for-loop:

writer.Write([]string{TestTable.id, TestTable.testId, TestTable.testtwoId, TestTable.testthreeId, TestTable.testfourId})

If some of those fields of TestTable are not strings, you have to convert them to strings as necessary.

edited Sep 18, 2019 at 16:42

Jonathan Hall

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answered Sep 18, 2019 at 2:25

Burak Serdar

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