# Example Example below will return records where **studentId=50**. ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": 50}}' \ https://api.appery.io/rest/1/db/collections/todo/query ``` ```json [ { "_id":"5278cb01e4b01085e4b7945d", "_createdAt":"2013-11-05 10:40:01.184", "_updatedAt":"2015-06-18 12:06:10.177", "marks":[ 7.0, 6.0, 5.0 ], "studentId":50.0, "studentName":"Dan" } ] ``` The **where** parameter also supports the following comparison values: - $lt – less than. - $lte – less than or equal to. - $gt – greater than. - $gte – greater than or equal to. - $ne – not equal to. - $in – contained in. - $nin – not contained in. - $exists – a value is set for the key. - $not – not match the expression. ## Less than ($lt) If you want to get only the students where the **studentId** is less than ***50*** ($lt): ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$lt": 50}}}' \ https://api.appery.io/1/db/collections/students/query ``` The result is only the students with student ID of 10, 20, 30, and 40. ## Less than or equal to ($lte) If you want to get only students where the **studentId** is less than or equal to ***50*** ($lte): ```curl curl -X POST \ -H "X-Appery-Database-Id: 526fdbd8e4b07c3286b537f1" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$lte": 50}}}' \ https://api.appery.io/1/db/collections/students/query ``` The result is the same as the previous example, except now it also includes ***50***. ## Greater than ($gt) Going the opposite way, if you want to show all students with a **studentId** of greater than ***50*** ($gt): ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$gt": 50}}}' \ https://api.appery.io/1/db/collections/student/query ``` This would return objects with IDs of **60**, **70**, **80**, **90**, and **100**. ## Greater than or equal to ($gte) Using **greater than or equal to** ($gte) is very similar: ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$gte": 50}}}' \ https://api.appery.io/1/db/collections/students/query ``` ## Not equal to ($ne) By using **not equal to** ($ne), you can specify which object you don’t want to select: You will get all the student objects except the student with the ID of 20. ## Contained in ($in) To get specific objects, use contained in ($in): ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$in": [20,80]}}}' \ https://api.appery.io/1/db/collections/students/query ``` This will return only student objects with IDs of 20 and 80 ## Not contained in ($nin) The **opposite** of **contained in** ($in) is **not contained in** ($nin): ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$nin": [20,80]}}}' \ https://api.appery.io/1/db/collections/students/query ``` This would return all objects besides objects with IDs of 20 and 80. ## A value is set ($exists) $exists option checks whether a value is set for a column: ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$exists":true}}}' \ https://api.appery.io/1/db/collections/students/query ``` ## As every object has the ID set, the above query would return the entire list. Or, specifying `false`, it would return an empty list, as every object has the student ID set. ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$exists":false}}}' \ https://api.appery.io/1/db/collections/students/query ``` ## Not match the expression ($not) **$not** performs a logical NOT operation on the specified operator expression and selects the documents that do not match the operator expression. This request will return all records where **studentId** is NOT greater than ***30***. ```curl curl -X POST \ -H "X-Appery-Database-Id: 544a5cdfe4b03d005b6233b9" \ -H "Content-Type: application/json" \ -d '{"where":{"studentId": {"$not":{"$gt":30 }}}}' \ https://api.appery.io/1/db/collections/students/query ```