User-Defined Variables (@vars) allow a user to create a variable within the session (outside of stored procedures) and share it between several queries and programs. In other words, you can store a value in a user-defined variable in one statement and refer to it later in another statement. This is useful for developers and also for migration purposes since this feature exists in other database products.
Note: A member of the MemSQL team has filed this feature request. We are adding in several features to this forum that we believe are popular with our users to engage and better understand the needs of the MemSQL community.