system.one - ClickHouse Documentation

Description

This table contains a single row with a single dummy UInt8 column containing the value 0. This table is used if a SELECT query does not specify the FROM clause. This is similar to the DUAL table found in other DBMSs.

Columns

dummy (UInt8)

Example

SELECT * FROM system.one LIMIT 10;

┌─dummy─┐
│     0 │
└───────┘

1 rows in set. Elapsed: 0.001 sec.

Last modified on August 3, 2026