CODEWITHSUNDEEP
sqlmysqlsqlite
David Homes
David Homes

Reputation: 2796

SQLite3 (or general SQL) retrieve nth row of a query result

Quicky question on SQLite3 (may as well be general SQLite)

How can one retrieve the n-th row of a query result?

row_id (or whichever index) won't work on my case, given that the tables contain a column with a number. Based on some data, the query needs the data unsorted or sorted by asc/desc criteria.

But I may need to quickly retrieve, say, rows 2 & 5 of the results.

So other than implementing a sqlite3_step()==SQLITE_ROW with a counter, right now I have no idea on how to proceed with this.

And I don't like this solution very much because of performance issues.
So, if anyone can drop a hint that'd be highly appreciated.

Regards david

Upvotes: 19

Views: 14557

Answers (3)

Lukasz Szozda
Lukasz Szozda

Reputation: 176124

But I may need to quickly retrieve, say, rows 2 & 5 of the results.

In scenario when you need non-continuous rows you could use ROW_NUMBER():

WITH cte AS (
  SELECT *, ROW_NUMBER() OVER() AS rn --OVER(ORDER BY ...) --if specific order is required
  FROM t
)
SELECT c 
FROM cte
WHERE rn IN (2,5);  -- row nums

db<>fiddle demo

Upvotes: 1

MPelletier
MPelletier

Reputation: 16699

The general approach is that, if you want only the nth row of m rows, use an appropriate where condition to only get that row.

If you need to get to a row and can't because no where criteria can get you there, your database has a serious design issue. It fails the first normal form, which states that "There's no top-to-bottom ordering to the rows."

Upvotes: 0

wlk
wlk

Reputation: 5785

add LIMIT 1 and OFFSET <n> to the query
example SELECT * FROM users LIMIT 1 OFFSET 5132;

Upvotes: 38

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