Import data from CSV file to postgres database according to conditions

Question

Can you please tell me if there is a way to export data from CSV file to postgress database according to conditions?

By condition I mean a situation where there are two tables in a postgres database. I have to do a validation before adding a row to the second table. I need to check that a parameter in my file matches the value in the first table and only if that parameter matches I need to put that parameter in the second table.

For example, I have two tables "clothing brand" and "clothing size". The CSV file that needs to be exported to postgres table contains both the brand of clothing and its sizes. I need to make a validation in the tables already created in postgres, that if the brand of clothing that is in the csv file exists already in the table, then I need to add or modify the table "clothing size".

I tried searching the internet, but found examples of how to simply import a complete table from CSV file to postgres database. any way to import a csv file to postgresql without creating new tables from scratch? How to import CSV file data into a PostgreSQL table https://www.youtube.com/watch?v=KKjcwBUxZXY But I couldn't find an example where I could first check the existing table data and only after successful results of this verification I could insert a specific row.

thank you. Could you please advise me how this trigger could read the value of CSV file at runtime on postgres database? — Andrei
– Andrei, Commented Mar 20, 2024 at 0:29
You are going to need to provide more information. 1) The table definitions. 2) Example data. 3) Example (pseudo)code of what you are trying to achieve. Add information as text as update to question text. — Adrian Klaver
– Adrian Klaver, Commented Mar 20, 2024 at 4:23

Simon Perepelitsa · Accepted Answer · 2024-03-20 09:16:47Z

1

The easiest solution is to import all data into a temporary table using COPY command, and then use standard SQL queries to filter out and insert only specific rows. It would look something like this:

create table temp_sizes (...);
copy temp_sizes from 'sizes.csv' format CSV;
insert into sizes from temp_sizes where brand_name in (select name from brands);
drop table temp_sizes;

Alternatively, you could use any general-purpose programming language to parse the CSV file and issue INSERT commands according to your conditions.

answered Mar 20, 2024 at 9:16

Simon Perepelitsa

20.7k8 gold badges58 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Import data from CSV file to postgres database according to conditions

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related