The SQLite count() function can be used to return the number of rows in a result set.
It can also be used to return the number of times a given column is not NULL in the result set.
It can be used in two ways. If you pass in the asterisk (*) wildcard character, it will return the total number of rows in the group. If you provide the name of a column, it will return the number of times that column is not NULL.
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 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.
One of the T-SQL functions introduced in SQL Server 2017 is the STRING_AGG() function. This is basically the equivalent of MySQL’s GROUP_CONCAT() function – it lets you return query results as a delimited list, rather than in rows.
But there are a few minor differences between the two functions.
This article explores some of the main syntax differences between these functions.
Before SQL Server 2017 came along, there wasn’t a T-SQL equivalent of the MySQL GROUP_CONCAT() function. This function allows you to return a result set as a comma-separated list, as opposed to listing each row as a separate row (as with a normal result set).
Prior to SQL Server 2017, if you wanted to put your result into a comma separated list, you’d need to find a workaround, perhaps using a combination of STUFF() and FOR XML PATH().
However, T-SQL now has the STRING_AGG() function which is available from SQL Server 2017. This function does pretty much the same thing as MySQL’s GROUP_CONCAT() function (with some minor differences).
Starting with SQL Server 2017, you can now make your query results appear as a list. This means you can have your result set appear as a comma-separated list, a space-separated list, or whatever separator you choose to use.
While it’s true that you could achieve this same effect prior to SQL Server 2017, it was a bit fiddly.
Transact-SQL now has the STRING_AGG() function, which concatenates the values of string expressions and places separator values between them. This works in much the same way to MySQL’s GROUP_CONCAT() function.
This article provides examples that demonstrate the T-SQL STRING_AGG() function.
In MySQL, you can return your query results as a comma separated list by using the GROUP_CONCAT() function.
The GROUP_CONCAT() function was built specifically for the purpose of concatenating a query’s result set into a list separated by either a comma, or a delimiter of your choice.
This article provides examples of how it all works.
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When working with databases, sometimes you want to find out how many rows will be returned by a query, without actually returning the results of the query. Or sometimes you might just want to find out how many rows are in a given table.
In SQL Server, you can use T-SQL‘s COUNT() function to return the number of rows that would be returned in a query.