Let’s say you want to set a variable ROOT_DIR that is used within another script. You would do this:
\set ROOT_DIR /path/to/directory
And to reference the variable:
\echo 'ROOT_DIR => ' :ROOT_DIR
Now, everywhere you might hardcode /path/to/directory in your scripts like this:
\i /path/to/directory/my_script_customer_ABC.sql
You can substitute it with the ROOT_DIR script variable:
\i :ROOT_DIR/my_script_customer_ABC.sql
And you can combine multiple variables:
\set ROOT_DIR /path/to/directory \set CUSTOMER_ID ABC \i :ROOT_DIR/my_script_customer_:CUSTOMER_ID.sql
Hope you enjoyed this quick PostgreSQL tip! If you did, click the Like button.
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j steven perry, The Blog 