It is used to calculate the encryption and decryption columns and it is the logical identifier of the column in SQL. Logical columns contain ciphertext columns (mandatory), query-helper columns (optional), like-query columns (optional), and plaintext columns (optional).
Encrypted data columns.
It is a helper column used for queries. For some non-idempotent encryption algorithms with higher security levels, irreversible idempotent columns are provided for queries.
It is a helper column used for like queries.