!startswith operator

Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel

Filters a record set for data that doesn't start with a case-insensitive search string.

The following table compares the startswith operators using the abbreviations provided:

Operator	Description	Case-Sensitive	Example (yields `true`)
`startswith`	RHS is an initial subsequence of LHS	No	`"Fabrikam" startswith "fab"`
`!startswith`	RHS isn't an initial subsequence of LHS	No	`"Fabrikam" !startswith "kam"`
`startswith_cs`	RHS is an initial subsequence of LHS	Yes	`"Fabrikam" startswith_cs "Fab"`
`!startswith_cs`	RHS isn't an initial subsequence of LHS	Yes	`"Fabrikam" !startswith_cs "fab"`

For more information about other operators and to determine which operator is most appropriate for your query, see datatype string operators.

Performance tips

Note

Performance depends on the type of search and the structure of the data. For best practices, see Query best practices.

When possible, use the case-sensitive !startswith_cs.

T | where column !startswith (expression)

Name	Type	Required	Description
T	`string`	✔️	The tabular input whose records are to be filtered.
column	`string`	✔️	The column by which to filter.
expression	scalar	✔️	The scalar or literal expression for which to search.

Rows in T for which the predicate is true.

StormEvents
| summarize event_count=count() by State
| where State !startswith "i"
| where event_count > 2000
| project State, event_count

Output