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

LEN([label])

label	quantity	amount	flag
cedar cedar	65	12.8	True
ORCHID-west	66	-7.6	False
maple-east	67	0	null
willow north	68	25.3	True
birch-birch	69	4.9	False
pine/south	70	-1.2	null
ash	71	9	True
null	null	null	null

SELECT length(label) AS result FROM input

Runs the example above.

SELECT LENGTH(label) AS result FROM input

Written for this dialect; not run here.

SELECT length(label) AS result FROM input

Written for this dialect; not run here.

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

Where a naive translation goes wrong

Replacing LEN with length(trim(label)) changes the shown values or null handling.
Naive SQL
```
SELECT length(trim(label)) AS result FROM input
```
result
11
11
10
12
11
10
3
null
Matches the calculation
```
SELECT length(label) AS result FROM input
```
result
15
11
10
12
11
10
3
null

LEN(string)