I'm using psql to check if a table exists in a given database. The command below works fine to return t for True or f for False:
psql -U $user -d $db -t -c "SELECT EXISTS (
SELECT FROM pg_tables WHERE tablename='$wanted');"
When the table doesn't exist, I get 'f'.
Instead, I would like psql to exit with a non-zero exit status if the query returned False.
Is that possible?
In general, I try to avoid provoking errors from SQL queries. Rather, I aim to work with the results they return and make sense of them.
That said, you could (quite hacky approach!) provoke a division by zero:
SELECT (1 / (SELECT count(*) FROM pg_tables WHERE tablename='$wanted'))::int::boolean;
If a table with the desired name is not existing, the query will fail with ERROR: division by zero. If a table with the desired name is existing, the query will return true.
Try this:
psql -U $user -d $db -t -c "select * from '$wanted' limit 1"
echo $?
If the table does not exist the exit code is 1.
