I have a .txt file where data present in below format: 
[customer]
customer_id=121  # this is primary key.
customer_name=abc
customer_age=25
[item]
item_id=222 # this is primary key.
sugar=100
stock=yes

[download]
Here 'customer' and 'item' are table names, this is external .txt file. I have to read this file and write the update statement to update the customer and update the corresponding values of table, the same applicable to to 'item' table as well and this I have to do based on primary key I have mentioned in the .txt file. what is best approach to do this.

In reply to reading txt and update into database table by Anonymous Monk

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