Listagg in Oracle to return distinct values
For clear-cut usage of LISTAGG
with distinct values in Oracle:
This grain of wisdom will make LISTAGG
focus only on distinct records, providing a comma-separated aggregation of unique values from your_table
.
Further down the rabbit hole of distinct LISTAGG
The fast solution fits the bill for the most clear-cut scenario. But, de Bono's hats aren't black and white only; there are shades, nuances - and so does LISTAGG
.
More columns? No problem!
When juggling with multiple columns, you often want distinct combinations:
Chew before you swallow: Handling large datasets
Oracle can be a picky eater and has a limit on the size of strings it happily ingests from LISTAGG
. For large datasets, you might prefer to use the CAST
function or slice and dice the data into smaller bites.
May the Performance be with you: testing distinct LISTAGG
Always trial run and tune your LISTAGG
implementations as subqueries or additional analytic functions may eat away your execution speed and resource pie. I'd go for the biggest piece, wouldn't you?
Mastering the art of distinct LISTAGG: techniques and alternatives
When life gives you Oracle 19c, make LISTAGG DISTINCT
Oracle 19c brought a cool feature: LISTAGG DISTINCT
, making our lives easier, just like a lemon squeezer:
Artisan crafting with COLLECT
and TABLE
functions
Our trusty sidekicks COLLECT
and TABLE
allow us to gather distinct values and convert them into a clean format for LISTAGG
:
The window to DISTINCT heaven
It's not always sunshine and rainbows, and ROW_NUMBER()
often comes to the rescue for filtering distinct values:
Sky's the limit? Not with CLOB!
Hitting a VARCHAR limit? Just convert CLOB
to VARCHAR
for grouping. Like turning water into wine, but SQL-style:
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