Database Management Systems
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().
When using JSON with SQL Server, you can use the JSON_QUERY() function to extract an object or an array from a JSON string.
To use this function, you provide the JSON expression as an argument. You can also provide a second (optional) argument to specify the object or array to extract.
When using JSON with SQL Server, you can use the JSON_VALUE() function to return a scalar value from a JSON string.
To use this function, you provide two arguments; the JSON expression, and the property to extract.
When using SQL Server, you can use the ISJSON() function to test whether or not a string expression contains valid JSON.
If the expression contains valid JSON, ISJSON() returns 1, otherwise it returns 0.
From SQL Server 2022, we also have the option of testing for a specific JSON type.
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