AVERAGE¶

The Avg aggregate function allows you to calculate the average value for a set of objects. To use the function, include Avg(columnNameInDatabase) into the list of properties requested from the server. For example, the following query retrieves an average box office earnings value for all movies in the database:

GET https://xxxx.backendless.app/api/data/Movie?props=Avg(totalBoxOffice)

The query returns the following result, notice the avg property in the returned object. The value of the property is the mathematical average of all values in the totalBoxOffice column:

[  
    {  
        "avg": 1813474455,  
        "___class": "Movie",  
    }  
]

Using Alias¶

To change the name of the returned property from avg to a custom name, use the following syntax:

Avg( columnNameInDatabase ) as customPropertyName

For example, the following query returns the average value in the averageTotalBoxOffice property:

Important

The value must be URL-encoded. The spaces are replaced with %20:

GET https://xxxx.backendless.app/api/data/Movie?props=Avg(totalBoxOffice)%20as%20averageTotalBoxOffice

The response for the query now contains the averageTotalBoxOffice property:

[  
    {  
        "averageTotalBoxOffice": 1813474455,  
        "___class": "Movie",  
    }  
]

Grouping Results¶

Results in the response can be grouped by values from another column. To request grouping of the results, add the groupBy parameter to the request with the value containing the name of the column. For example, the following request returns the average box office earnings value for the movies in the database grouped by the year the movies were released:

GET https://xxxx.backendless.app/api/data/Movie?props=Avg(totalBoxOffice),yearReleased&groupBy=yearReleased

The response for this request contains average earning values for the movies grouped by the release year:

[  
    {  
        "avg": 2207615668,  
        "yearReleased": 1997,  
        "___class": "Movie",  
    },  
    {  
        "avg": 2783918982,  
        "yearReleased": 2009,  
        "___class": "Movie",  
    },  
    {  
        "avg": 1341511219,  
        "yearReleased": 2011,  
        "___class": "Movie",  
    },  
    {  
        "avg": 1519479547,  
        "yearReleased": 2012,  
        "___class": "Movie",  
    },  
    {  
        "avg": 1663817556,  
        "yearReleased": 2015,  
        "___class": "Movie",  
    }  
]

Sorting¶

The results can be sorted using the sortBy parameter. For example, results for the following request will be sorted by the values in the yearReleased column in the descending order:

GET https://xxxx.backendless.app/api/data/Movie?props=Avg(totalBoxOffice),yearReleased&groupBy=yearReleased&sortBy=yearReleased%20DESC

To sort results by the aggregated value, assign a custom name to the column and sort by that name:

GET https://xxxx.backendless.app/api/data/Movie?props=Avg(totalBoxOffice)%20as%20averageTotal,yearReleased&groupBy=yearReleased&sortBy=averageTotal