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isnull()
Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel
Evaluates an expression and returns a Boolean result indicating whether the value is null.
Note
String values can't be null. Use isempty to determine if a value of type string
is empty or not.
Syntax
isnull(
Expr)
Learn more about syntax conventions.
Parameters
Name | Type | Required | Description |
---|---|---|---|
Expr | scalar | ✔️ | The expression to evaluate whether the value is null. The expression can be any scalar value other than strings, arrays, or objects that always return false . For more information, see The dynamic data type. |
Returns
Returns true
if the value is null and false
otherwise. Empty strings, arrays, property bags, and objects always return false
.
The following table lists return values for different expressions (x):
x | isnull(x) |
---|---|
"" |
false |
"x" |
false |
parse_json("") |
true |
parse_json("[]") |
false |
parse_json("{}") |
false |
Example
Find the storm events for which there's no begin location.
StormEvents
| where isnull(BeginLat) and isnull(BeginLon)
| project StartTime, EndTime, EpisodeId, EventId, State, EventType, BeginLat, BeginLon
Output
StartTime | EndTime | EpisodeId | EventId | State | EventType | BeginLat | BeginLon |
---|---|---|---|---|---|---|---|
2007-01-01T00:00:00Z | 2007-01-01T05:00:00Z | 4171 | 23358 | WISCONSIN | Winter Storm | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7067 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7068 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7069 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7065 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7070 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7071 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7072 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 2380 | 11735 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7073 | MINNESOTA | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 2240 | 10857 | TEXAS | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 2240 | 10858 | TEXAS | Drought | ||
2007-01-01T00:00:00Z | 2007-01-31T23:59:00Z | 1492 | 7066 | MINNESOTA | Drought | ||
... | ... | ... | ... | ... | ... | ... | ... |