Convert SQL Server result set into string
SQL Server 2017+ offers a built-in function called STRING_AGG
to conveniently concatenate rows with a defined separator:
However, for the brave souls who're stuck with an older version, we have FOR XML PATH
in our armory to perform the same task:
Starting right and type conversion
In the realm of string concatenation, especially in scenarios dealing with brutally large data sets, one must learn to initialize variables accurately. Also, respect the data types; don't mix them up like a bad cocktail!
- Use
NVARCHAR(MAX)
while declaring variables. UnlikeVARCHAR
, it won't leave your precious data hanging halfway. - Show love to
CAST
andCONVERT
. They're the secret sauce that turns non-string data into string before concatenation.
Concatenating in older versions
For those sporting outdated versions, you've two weapons: STUFF
and FOR XML PATH
. They're old but gold:
ISNULL
or COALESCE
are your knights in shining armor, preventing NULL values from ruining your concatenation party.
Handling every scenario like a pro
Fancy challenges like stray commas or inconsistent data types? Here's how you tackle it like a boss:
- Last comma problem: Use
LEFT
withLEN
to give that trailing comma a pink slip. - Filtering dilemma: Add a
WHERE
clause to act as a bouncer for your specific needs. - Dealing with NULLs: Put
ISNULL
orCOALESCE
in yourSELECT
statement -- they chew up NULLs for breakfast. - Code reusability: Get a patent for your logic by sticking it into a stored procedure. Then sit back and let output parameters do all the hard work.
More ways to play with concatenation
Let's pop the hood and see what other cool functionalities SQL Server concatenation offers:
- Structured output: Remember
FORMAT
function? It's the tailor who ensures all the numbers or dates in your string fit perfectly. - Hello, exact concatenation:
CONCAT
function does exactly what it says on the tin. Available from SQL Server 2012 onwards! - Caring for performance: Got a big dataset? Tread carefully. Large concatenations can make your server sweat!
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