Expected workflow

1. Add a SQL query/statement in queries.sql, following the other examples.
2. Run make sqlc using the same version of sqlc as in build/Dockerfile.codegen

sqlc decides what the return-type of the generated method should be based on the :exec suffix (documentation here):

• :exec will only tell you whether the query succeeded: error
• :execrows will tell you how many rows were affected: (int64, error)
• :one will give you back a single struct: (Author, error)
• :many will give you back a slice of structs: ([]Author, error)

It is configured by the sqlc.yaml file. You can read docs about the various options it supports here.