Bool

The Bool data type represents a truth value, storing either true or false. Internally, it is stored as an 8-bit unsigned integer (UInt8), where true corresponds to 1 and false to 0.

SELECT true AS col, toTypeName(col)

Result:

┌─col──┬─toTypeName(true)─┐
│ true │ Bool             │
└──────┴──────────────────┘

SELECT true == 1 AS col, toTypeName(col)

Result:

┌─col─┬─toTypeName(equals(true, 1))─┐
│   1 │ UInt8                       │
└─────┴─────────────────────────────┘
Updated