hi, @MichelDiz

How to calculate the interval between the date and 2020-05-21?

I want to run code like this, but it’s error…

```
math(since(date) - since(2020-05-21))
```

hi, @MichelDiz

How to calculate the interval between the date and 2020-05-21?

I want to run code like this, but it’s error…

```
math(since(date) - since(2020-05-21))
```

`since`

returns the number of seconds from the time specified as a float. Are you sure that’s what you want to do?

if you want to do the number of seconds since 2020-05-21, you could just do `since(2020-05-21)`

Although I am not exactly sure what you want to do

Both dates has to be present as predicates for the following to work. I could not get it to work by making one of them as variables (I am assuming that was perhaps your intention).

With this mutation:

```
{
set{
_:a <cdate> "2020-05-21" .
_:a <bdate> "2019-05-21" .
}}
```

this query returns results as below

```
query myDemoQuery() {
films(func: has(bdate)) {
pastDate as bdate
futureDate as cdate
futureSeconds as math(since(futureDate) )
pastSeconds as math(since(pastDate) )
difference: math(pastSeconds - futureSeconds )
}
}
```

Result:

```
{
"data": {
"films": [
{
"bdate": "2019-05-21T00:00:00Z",
"cdate": "2020-05-21T00:00:00Z",
"val(futureSeconds)": 11007887.911656,
"val(pastSeconds)": 42630287.911659,
"difference": 31622400.000003
}
]
}
}
```