Lustra::SQL::Query::Fetch

Fetch the result set row per row fetch_all optional parameter is helpful in transactional environment, so it stores the result and close the resultset before starting to call yield over the data preventing creation of a new connection if you need to call SQL into the yielded block.

# This is wrong: The connection is still busy retrieving the users:
Lustra::SQL.select.from("users").fetch do |u|
  Lustra::SQL.select.from("posts").where { u["id"] == posts.id }
end

# Instead, use `fetch_all`
# Lustra will store the value of the result set in memory
# before calling the block, and the connection is now ready to handle
# another query.
Lustra::SQL.select.from("users").fetch(fetch_all: true) do |u|
  Lustra::SQL.select.from("posts").where { u["id"] == posts.id }
end

Alias for first because first is redefined in Collection::Base object to return a model instead.

Fetch the data using CURSOR. This will prevent Lustra to load all the data from the database into memory. This is useful if you need to retrieve and update a large dataset.

Return the first line of the query as Hash(String, ::Lustra::SQL::Any), or nil if not found

Helpers to fetch a SELECT with only one row and one column return.

Return an array with all the rows fetched.