When creating percentage measures, it is often useful to make sure you are not dividing by zero in the percentage calculation. This can be done through the SQL function `NULLIF(expression_1, expression_2)`

.

`NULLIF`

takes two inputs. If the two expressions are equal, `NULLIF`

returns a **NULL**. If the two expressions are *not* equal, `NULLIF`

returns the value of the first expression.

So, in order to avoid dividing by zero in a dimension, we might use `NULLIF(${field_name}, 0)`

. This means "if `${field_name}`

is `0`

, give me a NULL, otherwise give me `${field_name}`

".

Here is an example of a percentage measure using `NULLIF`

:

```
- measure: percent_sold
type: number
format: "%.2f%"
sql: 100.0 * ${sold_count} / NULLIF(${count}, 0)
```