If you’re getting an error message that reads “The function ‘LAST_VALUE’ must have an OVER clause with ORDER BY.” when using the LAST_VALUE() function in SQL Server, it’s probably because you’ve omitted the ORDER BY clause from the OVER clause.
The LAST_VALUE() function requires an OVER clause that contains an ORDER BY clause. This error happens when we include the OVER clause but not the ORDER BY clause.
To fix this error, add an ORDER BY clause to the OVER clause.
Sometimes when we run a SQL query, we only want to see unique rows. But depending on the columns we’re selecting, we might end up with duplicate rows. And this could happen without even knowing it, especially with large data sets.
But it doesn’t have to be this way.
Fortunately most SQL databases provide us with an easy way to remove duplicates.
In SQL Server, we can use the TRIM() function to remove leading and trailing characters from a given string.
A common use case is to remove whitespace from the start and end of the string, but we can also specify other characters to remove.
Also, as from SQL Server 2022, we can specify which side of the string to remove the characters from (i.e. leading, trailing, or both).
In SQL Server, we can use the T-SQL RTRIM() function to remove trailing blanks from a given string. Trailing blanks are white spaces, tabs, etc that come at the end of the string.
Also, as from SQL Server 2022, we can specify other trailing characters to remove from the string.
In SQL Server, we can use the T-SQL LTRIM() function to remove leading blanks from a given string.
Also, as from SQL Server 2022, we can specify other leading characters to remove from the string.
If you’re getting SQL Server error msg 402 that tells you the “data types” are “incompatible in the approx_percentile_cont operator“, it’s probably because you’re trying to apply the APPROX_PERCENTILE_CONT() function against a non-numeric column (or one that doesn’t evaluate to a numeric type).
When using the APPROX_PERCENTILE_CONT() function, the ORDER BY expression in the WITHIN GROUP clause must evaluate to an exact or approximate numeric type. Other data types are not allowed, and will result in the above error.
To fix this issue, be sure to apply the function against a numeric column/expression.
In SQL Server STRING_SPLIT() is a table-valued function that splits a string into rows of substrings, based on a specified separator character.
Each substring is returned on its own row, in a column called value.
In SQL Server the CHOOSE() function returns the item at the specified index from a list of values.
If you’re getting SQL Server error 10754 that reads “The function ‘APPROX_PERCENTILE_CONT’ must have a WITHIN GROUP clause” it’s probably because you’re calling the APPROX_PERCENTILE_CONT() function, but you’ve omitted the WITHIN GROUP clause.
To fix this issue, add a WITHIN GROUP clause to the function (and make sure it has an ORDER BY clause).
The SQL COUNT() function is a handy tool for telling us how many rows would be returned in a query. We can pass a column name to the function or we can pass the asterisk (*) wildcard to indicate all columns.
If a column contains NULL values, we could get different results, depending on whether we use the column name or the asterisk (*).