1) @21.42 I'm using Postgres 14.10. Code on Ln17, had to use single quote for VALUES ( '${user_name}', '${pass_word}'). Double quote generated errors. 2) I use Thunder Client instead of Postman. After successful insertion with response in the terminal, Thunder client kept waiting for response.
The quotes depend on the SQL mode usage, they can be used for either enclosing string literals or enclosing identifiers such as table names or column names.