Explain EXPLAIN SYNTAX (children 1) SelectWithUnionQuery (children 1) ExpressionList (children 1) SelectQuery (children 2) ExpressionList (children 1) Asterisk (children 1) ColumnsTransformerList (children 1) ColumnsApplyTransformer TablesInSelectQuery (children 1) TablesInSelectQueryElement (children 1) TableExpression (children 1) Function numbers (children 1) ExpressionList (children 1) Literal UInt64_1