Understanding the Difference Between MAX() and GREATEST() in SQL Server

Posted on by Ian

SQL Server 2022 introduced the GREATEST() function that returns the maximum value from a list of values. You may be thinking, “but there’s already a MAX() function that returns the maximum value, so why the need for another function that does the same thing?”.

Well here’s the thing – they don’t do the same thing. They’re actually quite different functions, used in different scenarios.

If you’re wondering what the difference is between the MAX() and GREATEST() functions, read on to find out.

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SQL EXISTS Explained

Posted on by Ian

The SQL EXISTS predicate is used to specify a test for a non-empty set. It returns TRUE or FALSE, depending on the outcome of the test.

When we incorporate the EXISTS predicate operator into our SQL queries, we specify a subquery to test for the existence of rows. If there are any rows, then the subquery is TRUE. If there are no rows, then the subquery is FALSE.

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Fix Error “The function ‘FIRST_VALUE’ must have an OVER clause” in SQL Server

Posted on by Ian

If you’re getting an error that reads “The function ‘FIRST_VALUE’ must have an OVER clause” in SQL Server, it’s probably because you’re calling the FIRST_VALUE() function without an OVER clause.

The FIRST_VALUE() function requires an OVER clause (and that clause must have an ORDER BY clause).

To fix this issue, be sure to include an OVER clause when calling the FIRST_VALUE() function.

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Fixing Error 10754: “The function ‘APPROX_PERCENTILE_DISC’ must have a WITHIN GROUP clause” in SQL Server

Posted on by Ian

When using the APPROX_PERCENTILE_DISC() function in SQL Server, you may get an error that reads “The function ‘APPROX_PERCENTILE_DISC’ must have a WITHIN GROUP clause“. If you get this error, it’s because you omitted the WITHIN GROUP clause when using the APPROX_PERCENTILE_DISC() function.

To fix this issue, make sure you include the WITHIN GROUP clause whenever you use the APPROX_PERCENTILE_DISC() function.

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An Introduction to the IS [NOT] DISTINCT FROM Predicate in SQL Server

Posted on by Ian

SQL Server 2022 introduced the IS [NOT] DISTINCT FROM predicate that compares the equality of two expressions and guarantees a true or false result, even if one or both operands are NULL.

Normally if we compare two NULL values, they will always be different (although this will depend on your ANSI_NULLS setting – setting ANSI_NULLS to OFF will result in NULLs being treated as equal). The IS [NOT] DISTINCT FROM predicate enables us to compare NULLs as though they’re equal, even when our ANSI_NULLS setting is set to ON.

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CREATE TABLE IF NOT EXISTS Equivalent in SQL Server

Posted on by Ian

In SQL, we can use the CREATE TABLE IF NOT EXISTS statement to create a table only if it doesn’t exist. The benefit of doing this is that we won’t get an error if there’s already a table with the same name.

But SQL Server doesn’t support this syntax – at least not in the current version of SQL Server at the time of writing (SQL Server 2022) .

So with SQL Server, we need to do a bit of extra work.

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Fix “Argument value 0 is invalid for argument 3 of generate_series function” in SQL Server

Posted on by Ian

If you’re getting SQL Server error 4199 that reads “Argument value 0 is invalid for argument 3 of generate_series function“, it’s probably because you’re passing zero as the third argument to the GENERATE_SERIES() function.

The GENERATE_SERIES() function accepts an optional third argument, but this argument can’t be zero.

To fix this error, either pass a non-zero expression as the third argument, or omit the argument altogether (in order to use the default step of 1).

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Generate a Time Series in SQL Server

Posted on by Ian

SQL Server’s GENERATE_SERIES() function returns a series of numbers within a given interval. But just because it returns numbers, doesn’t mean we can’t leverage its functionality in order to generate a series of time values.

If you need to create a series of time values with evenly spaced intervals between a start and end point, maybe the following technique can help.

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