In SQL Server, the T-SQL DATEPART() function returns an integer that represents the specified datepart of the specified date. For example, you can pass in 2021-01-07 and have SQL Server return only the year portion (2021).
You can also extract the time portion. For example, you can pass in 2018-06-02 08:24:14.3112042 and have SQL Server return only the hour portion (8).
Examples below.
Continue readingSometimes when working with SQL Server (or any other DBMS for that matter), you need to return the short name for a month. By this I mean the 3 letter abbreviation of a month. For example, you need “Dec” instead of “December”.
Here are four ways you can extract the shortened month name from a date in SQL Server.
This article provides a solution to a problem you may occasionally encounter while using the DATEDIFF() function in SQL Server.
If you encounter the following error:
The datediff function resulted in an overflow. The number of dateparts separating two date/time instances is too large. Try to use datediff with a less precise datepart.
It’s because the return value is too large. The DATEDIFF() function returns its result as an int data type. The reason you got this message is that the return value is too big for the int data type. Fortunately there’s an easy way to fix this.
In MySQL, sometimes you don’t want NULL values to be returned as NULL. Sometimes you want NULL values to be returned with a different value, such as “N/A”, “Not Applicable”, “None”, or even the empty string “”.
Fortunately there are several ways to do this in MySQL.
Here are four:
IFNULL() functionCOALESCE() functionIF() function combined with the IS NULL (or IS NOT NULL) operatorCASE expression combined with the IS NULL (or IS NOT NULL) operatorExamples of these options are below.
When querying a SQL Server database, there may be times where you don’t want null values to be returned in your result set. And there may be times where you do want them returned. But there may also be times where you do want them returned, but as a different value.
That’s what the ISNULL() function is for.
ISNULL() is a T-SQL function that allows you to replace NULL with a specified value of your choice.
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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MySQL includes a COUNT() function, which allows you to find out how many rows would be returned from a query. This function is part of the SQL standard, and it can be used with most relational database management systems.
The COUNT() function can also be used to affect the results of a query if required, for example, by only returning those results that have a row count greater than a given amount.
This article contains examples of COUNT() usage in MySQL.