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!contains operator

Filters a record set for data that does not include a case-sensitive string. contains searches for characters rather than terms of three or more characters. The query scans the values in the column, which is slower than looking up a term in a term index.

The following table provides a comparison of the contains operators:

Operator Description Case-Sensitive Example (yields true)
contains RHS occurs as a subsequence of LHS No "Success Audit" contains "audit"
!contains RHS doesn't occur in LHS No "Success Audit" !contains "auditing"
contains_cs RHS occurs as a subsequence of LHS Yes "Success Audit" contains_cs "Audit"
!contains_cs RHS doesn't occur in LHS Yes "Success Audit !contains_cs "auD"

The following abbreviations are used in the table above:

  • RHS = right hand side of the expression
  • LHS = left hand side of the expression

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

Case-insensitive operators are currently supported only for ASCII-text. For non-ASCII comparison, use the tolower() function.

Performance tips

Performance depends on the type of search and the structure of the data.

For faster results, use the case-sensitive version of an operator, for example, contains_cs, not contains.

If you're testing for the presence of a symbol or alphanumeric word that is bound by non-alphanumeric characters at the start or end of a field, for faster results use has or in. Also, has works faster than contains, startswith, or endswith, however it is not as precise and could provide unwanted records.

Syntax

Case insensitive syntax

T | where Column !contains (Expression)

Arguments

  • T - The tabular input whose records are to be filtered.
  • Column - The column to filter.
  • Expression - Scalar or literal expression.

Returns

Rows in T for which the predicate is true.

Example

events
    | project original_time, data_source_name, name
    //--- Search for the last 5 mins of data    
    | where original_time > now(-5m)
    // Look for events with unsuccessful audit
    | where name !contains "success" 
    | take 2

Results

original_time data_source_name name
2023-04-13T13:59:29.732Z microsoftWindowsSource2 Failure Audit: An account failed to log on
22023-04-13T13:59:30.900Z microsoftWindowsSource2 Failure Audit: An account failed to log on