how to insert multiple columns in a single column of another table in sql

All we need is an easy explanation of the problem, so here it is.

I have the following table:

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Then I want to get the following:

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I want to achieve this in postgres. What should I do?

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

Tabular data can be easily unpivoted with the help of JSON functions.

The query below will work, assuming tablename is replaced by your table name, and primary_key is the name of the pivot column. The other columns don’t have to be specified, they’re obtained automatically by json_each_text applied to row_to_json applied to all rows.

SELECT primary_key, key, value
 FROM (select row_to_json(t.*) AS line, primary_key
     FROM tablename AS t) AS r
   JOIN LATERAL json_each_text(r.line)
     ON (key <> 'primary_key')

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

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