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Aggregate Functions

 

General queries within Hydro GeoAnalyst may include an aggregate functions. The following functions are available:

AVG: Returns the average value of a numeric expression evaluated over a set.

COUNT: Returns the number of items in a collection.

MAX: Returns the maximum value of a numeric expression evaluated over a set.

MIN: Returns the minimum value of a numeric expression evaluated over a set.

STDEV: Returns the sample standard deviation of a numeric expression evaluated over a set.

STDDEVP: Returns the population standard deviation of a numeric expression evaluated over a set.

SUM: Returns the sum of a numeric expression evaluated over a set.

VAR: Returns the sample variance of a numeric expression evaluated over a set, using the unbiased population formula.

VARP: Returns the population variance of a numeric expression evaluated over a set, using the biased population formula.

 

You can specify the function within the Query Builder by selecting the appropriate function in the Display Fields section, in the Function column for the appropriate field.

 

 

 

When executing a query containing an aggregate function, the query builder will automatically group all other fields in the Display Fields. This is required in order to be able to determine/calculate the function for the selected field.

In the example above, the query will be grouped by the station name - so only one record per station name will be displayed - the record with the maximum depth to water level for each station.

 

 


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