To get help from the built-in system, type .help when in the beanquery client

beanquery> .help

Shell utility commands (type help <topic>):
===========================================
EOF    describe  exit     format  history  parse  reload  set
clear  errors    explain  help    output   quit   run     tables

Beancount query commands:
=========================
balances  from  journal  print  select  targets  where

beanquery>

To get help on a specific command type .help <command name> E.g.:

beanquery> .help select
Extract data from a query on the postings.

The general form of a SELECT statement loosely follows SQL syntax, with
some mild and idiomatic extensions:
.........

To get the list of tables available in beanquery, type .tables

beanquery> .tables
accounts
balances
commodities
documents
entries
events
notes
postings
prices
transactions
beanquery>

To see the list of columns available in a table, type .describe <table name> For example, to see the columns in the postings table, type

beanquery> .describe postings
table postings:
  type (str)
  id (str)
  date (date)
  year (int)
  month (int)
  day (int)
  filename (str)
  lineno (int)
  location (str)
  flag (str)
  payee (str)
  narration (str)
  description (str)
  tags (set)
  links (set)
  posting_flag (str)
  account (str)
  other_accounts (set)
  number (decimal)
  currency (str)
  cost_number (decimal)
  cost_currency (str)
  cost_date (date)
  cost_label (str)
  position (position)
  price (amount)
  weight (amount)
  balance (inventory)
  meta (dict)
  entry (transaction)
  accounts (set[str])
beanquery>

To see the list of columns in the transactions table type:

beanquery> .describe transactions
table transactions:
  meta (metadata)
  date (date)
  flag (str)
  payee (str)
  narration (str)
  tags (set)
  links (set)
  accounts (set[str])
beanquery>