CSV File & Normalization

Hi Guys …
I encounter some process that I didn’t where should I start .
My problem is :
I have tables … this tables is in a normalize form
so I just thinking how can I import a CSV file from this tables ??
If I try to perform many queries… I guess this can create a performance issue :frowning:

Either use JOIN in your query to denornalize the data and write the denornalized data to the CSV, or create one CSV per table.

I didn’t get it …
First I write a query to and join those values ??
then create new ?
then insert it to the normalized table?

No you write a query that JOINs multiple tables, and then you write the result to a file.


I would create a temporary table that represents the exact csv file structure. I would then populate that table through x number of queries as needed. Once the table had all the data export/write it to a csv file which would be trivial once all the data is in the temp table. In terms of multiple values these are three approaches I have taken in the past.

1.) For simple values use a delimiter and stuff everything in a single column in the csv file.



2.) Allocate a number of columns that will never be exceeded.

color_1 | color_2 | color_3 | color_4

red . | blue . | black . | green

3.) For complex relational data using a separate csv might be best.


product_id | color

123 . | . red
123 . | blue
123 . | black
123 . | green

When I’m asked to generate a csv file like this I always tend to question whether something else would be a better solution. It all depends on the circumstance. Better approaches can include a service layer (sharing data with vendors) or perhaps even a json file instead of csv. Everyone seems to always default to a csv file when there might be other solutions are that are more appropriate.

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Thank you so much for this kind of Idea …

MySQL can also export CSV directly (SELECT ... INTO OUTFILE ...): https://dev.mysql.com/doc/refman/8.0/en/select-into.html

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