MariaDB includes two selectors that enable us to select elements from JSON arrays:
[N] selects element number N in the array (for example, [0] to select the first element). [*] selects all elements in the array.These can be used in a number of JSON functions that are included in MariaDB. The following examples use them with the JSON_EXTRACT() function in order to return selected array elements.
In Oracle Database, the JSON_ARRAYAGG() function creates a JSON array from a column of SQL expressions.
In Oracle Database, the JSON_ARRAY() function creates a JSON array from a sequence of SQL scalar expressions or one collection type instance, VARRAY or NESTED TABLE.
In MariaDB, JSON_ARRAY_APPEND() is a built-in function that appends values to the end of the specified array/s within a JSON document, and returns the result.
In MariaDB, JSON_ARRAY_INSERT() is a built-in function that inserts a value into a JSON document and returns the result.
In MariaDB, JSON_ARRAYAGG() is a built-in function that returns a JSON array containing an element for each value in a given set of JSON or SQL values.
The function acts on a column or an expression that evaluates to a single value. It enables you to aggregate a result set as a single JSON array. Each row of the result set ends up as a single element in the array.
Continue readingIn MariaDB, JSON_ARRAY() is a built-in function that returns a JSON array containing the specified values, provided as arguments.
If you get the “$pullAll requires an array argument but was given a double” error in MongoDB, it’s because you didn’t provide an array as the value to replace.
Continue readingMongoDB provides a few operators that enable you to remove values from arrays.
These include:
$pull$pullAll$popIf you have a collection of documents in MongoDB that contain arrays, you can add new values to those arrays if required.
Depending on your specific requirements, you can use the $push operator or the $addToSet operator.