aggregateClause

The aggregate clause accumulates a running value across query rows. An optional starting clause provides an initial accumulator value.

Examples

Sum values with starting value

from [Observation] O
  aggregate Total starting 0: $total + O.value

Count distinct values

from [Condition] C
  aggregate distinct Count starting 0: $total + 1

Build a concatenated string

from Codes C
  aggregate Result starting '': $total + C.code + ', '

Railroad Diagram

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aggregateClause
  : 'aggregate' ('all' | 'distinct')? identifier startingClause? ':' expression
  ;