Database Management Systems
Among the many MySQLÂ aggregate functions is one called JSON_ARRAYAGG(). This function 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.
The order of the elements in the array is undefined.
In MySQL, the difference between the MIN() and LEAST() functions is exactly the same as the difference between the MAX() and GREATEST() functions.
In each case, both functions perform a similar operation, but they do have a different syntax.
At first glance, the MySQL MAX() and GREATEST() functions perform a similar operation. They both return the maximum value from a range of values. However, there’s a difference between these two functions.
The best way to see the difference between these two functions is to compare their syntax.
The MySQL LEAST() function is a comparison function that returns the smallest value from a list of values.
The list of values is provided as multiple arguments. So in other words, LEAST() returns the minimum-valued argument from a list of arguments.
The MySQL GREATEST() function is a comparison function that returns the largest value from a list of values.
The list of values is provided as multiple arguments. So in other words, GREATEST() returns the maximum-valued argument from a list of arguments.
The MySQL MIN() function is an aggregate function that returns the minimum value from an expression.
Typically, the expression would be a range of values returned as separate rows in a column, and you can use this function to find the minimum value from the returned rows. If there are no matching rows, MIN() returns NULL.
For example, you can use this function to find out which city has the smallest population out of a list of cities.
The MySQL MAX() function is an aggregate function that returns the maximum value from an expression.
Typically, the expression would be a range of values returned as separate rows in a column, and you can use this function to find the maximum value from the returned rows. If there are no matching rows, MAX() returns NULL.
For example, you can use this function to find out which city has the largest population out of a list of cities.
If you’ve been using the JSON_MODIFY() function to modify JSON documents in SQL Server, you might be used to modifying the value part of a key/value property. But did you know that you can also modify the key part?
The trick to doing this is to copy the value to a new key, then delete the old key.
Examples below.
In SQL Server, you can use the T-SQLÂ JSON_MODIFY() function to modify the value of a property in a JSON string. The function returns the updated JSON string.
Two of the many T-SQL functions available in SQL Server are JSON_QUERY() and JSON_VALUE(). These functions can be used to extract data from JSON documents.
Their general syntax is similar, and at first glance, you might think they do exactly the same thing, but they don’t. There’s definitely a place for both functions when working with JSON and SQL Server.
This article looks at the difference between JSON_QUERY() and JSON_VALUE().