When querying your App Services data, you can use your query string to get the data, then sort and manage it on the client. This topic describes a few useful techniques.
Note: For introductory information about queries, be sure to see App Services data query overview.
Note: Query examples in this content are shown unencoded to make them easier to read. Keep in mind that you might need to encode query strings if you're sending them as part of URLs, such as when you're executing them with the cURL tool.
Your query can return multiple kinds of values -- such as the values of multiple properties -- by specifying the property names in your select statement as a comma-separated list.
For example, the following request returns the address and phone number of users whose name is Gladys Kravitz:
/users?ql="select address,phone_number where name = 'Gladys Kravitz'"
Your query can search the text of entity values of the string data type. For example, you can search a postal code field for values that start with a specific three numbers.
For example, the following query selects all restaurants with the word
diner in the name:
/restaurants?ql="select * where name contains 'diner'"
Note: Not all string properties of the default entities are indexed for searching. This includes the
The following table lists a few examples of the kind of searches you can do in queries.
|Find users whose name value contains the full word "Kravitz".||
/users?ql="select * where name contains 'Kravitz'"
|Find users whose name value contains a word that starts with "Krav".||
/users?ql="select * where name contains 'Krav*'"
|Find users whose name value is exactly and only "Gladys Kravitz".||
/users?ql="select * where name = 'Gladys Kravitz'"
If you've stored location data with your entities, you can query for the proximity of the geographical locations those entities represent. For more information on geolocation, see Geolocation.
|Find stores whose locations are within the specified longitude and latitude.||
/stores?ql="location within .5 of 40.042016, -86.900749"
The return results are sorted in order of nearest to furthest. If there are multiple entries at the same location, they're returned in the order they were added to the database.
For more on geolocation queries, see Geolocation.
You can return query results that are sorted in the order you specify. Use the
order by clause to specify the property to sort by, along with the order in which results should be sorted. The syntax for the clause is as follows:
order by <property_name> asc | desc
The following table includes a few examples:
|Sort by first name in ascending order||
/users?ql="select * where lastname = 'Smith' order by firstname asc"
|Sort by first name in descending order||
/users?ql="select * where lastname = 'Smith' order by firstname desc"
|Sort by last name, then first name in ascending order||
/users?ql="select * where lastname contains 'Sm*' order by lastname asc, firstname asc"
When your query might return more results than you want to display to the user at once, you can use the limit parameter with cursors or API methods to manage the display of results. By default, query results are limited to 10 at a time. You can adjust this by setting the limit parameter to a value you prefer.
For example, you might execute a query that could potentially return hundreds of results, but you want to display 20 of those at a time to users. To do this, your code sets the limit parameter to 20 when querying for data, then provides a way for the user to request more of the results when they're ready.
You would use the following parameters in your query:
Number of results to return. The maximum number of results is 1,000. Specifying a limit greater than 1,000 will result in a limit of 1,000.
Limit is applied to the collection, not the query string. For example, the following query will find the first 100 entities in the books collection, then from that set return the ones with author='Hemingway':
/books?ql="author = 'Hemingway'&limit=100"
You can also use the limit parameter on a request without a query string. The following example is shorthand for selecting all books and limiting by 100 at a time:
Using a limit on a DELETE can help you manage the amount of time it takes to delete data. For example you can delete all of the books, 1000 at a time, with the following:
Keep in mind that DELETE operations can take longer to execute. Yet even though the DELETE query call might time out (such as with a very large limit), the operation will continue on the server even if the client stops waiting for the result.
||string||An encoded representation of the query position pointing to a set of results. To retrieve the next set of results, pass the cursor with your next call for most results.|
Select all users whose name starts with fred, and returns the first 50 results:
/users?ql="select * where name = 'fred*'&limit=50"
Retrieve the next batch of users whose name is "fred", passing the cursor received from the last request to specify where the next set of results should begin:
/users?ql="select * where name = 'fred*'&limit=50&cursor=LTIxNDg0NDUxNDpnR2tBQVFFQWdITUFDWFJ2YlM1emJXbDBhQUNBZFFBUUQyMVZneExfRWVLRlV3TG9Hc1doZXdDQWRRQVFIYVdjb0JwREVlS1VCd0xvR3NWT0JRQQ"