COT in Tableau: the SQL equivalent, with a worked example

COT([score])

id	amount	units	score	other
1	-2.5	2	-0.8	3
2	0	0	0	4
3	1.5	3	0.25	2
4	4	4	0.5	8
5	9	5	0.8	11
6	16	6	1	14
7	null	7	null	9
8	4	8	-0.5	null

SELECT CASE WHEN score=0 THEN NULL ELSE 1/tan(score) END AS result FROM input ORDER BY id

Runs the example above.

SELECT CASE WHEN score=0 THEN NULL ELSE 1/tan(score) END AS result FROM input ORDER BY id

Written for this dialect; not run here.

SELECT CASE WHEN score=0 THEN NULL ELSE 1/tan(score) END AS result FROM input ORDER BY id

Written for this dialect; not run here.

id	amount	units	score	result
1	-2.5	2	-0.8	-0.971215
2	0	0	0	null
3	1.5	3	0.25	3.91632
4	4	4	0.5	1.83049
5	9	5	0.8	0.971215
6	16	6	1	0.642093
7	null	7	null	null
8	4	8	-0.5	-1.83049

Same rows from the calculation and from the SQL in DuckDB.

Where a naive translation goes wrong

Replacing null results with zero changes missing-value semantics.
Naive SQL
```
SELECT coalesce((CASE WHEN score=0 THEN NULL ELSE 1/tan(score) END),0) AS result FROM input ORDER BY id
```
id amount units score result
1 -2.5 2 -0.8 -0.971215
2 0 0 0 0
3 1.5 3 0.25 3.91632
4 4 4 0.5 1.83049
5 9 5 0.8 0.971215
6 16 6 1 0.642093
7 null 7 null 0
8 4 8 -0.5 -1.83049
Matches the calculation
```
SELECT CASE WHEN score=0 THEN NULL ELSE 1/tan(score) END AS result FROM input ORDER BY id
```
id amount units score result
1 -2.5 2 -0.8 -0.971215
2 0 0 0 null
3 1.5 3 0.25 3.91632
4 4 4 0.5 1.83049
5 9 5 0.8 0.971215
6 16 6 1 0.642093
7 null 7 null null
8 4 8 -0.5 -1.83049

COT(number)