Query wrapper on query that saves query itself and it's name.

Client Database client.

DB interface to work with db.

NamedExecer used for work with structs with named tags.

Pinger used to check db connection.

QueryExecer used for plain queries.

SQLExecer combines NamedExecer and QueryExecer.

Transactor interface for transactions.

TxManager transaction manager that calls passed functions as handler.

Handler - function called in transaction.