你当前正在访问 Microsoft Azure Global Edition 技术文档网站。 如果需要访问由世纪互联运营的 Microsoft Azure 中国技术文档网站，请访问 https://docs.azure.cn。
!hasprefix operators
Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel
Filters a record set for data that doesn't include a case-insensitive starting string.
For best performance, use strings of three characters or more. !hasprefix searches for indexed terms, where an indexed term is three or more characters. If your term is fewer than three characters, the query scans the values in the column, which is slower than looking up the term in the term index.
The following table compares the hasprefix operators using the abbreviations provided:
- RHS = right-hand side of the expression
- LHS = left-hand side of the expression
| Operator | Description | Case-Sensitive | Example (yields true) |
|---|---|---|---|
hasprefix |
RHS is a term prefix in LHS | No | "North America" hasprefix "ame" |
!hasprefix |
RHS isn't a term prefix in LHS | No | "North America" !hasprefix "mer" |
hasprefix_cs |
RHS is a term prefix in LHS | Yes | "North America" hasprefix_cs "Ame" |
!hasprefix_cs |
RHS isn't a term prefix in LHS | Yes | "North America" !hasprefix_cs "CA" |
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 !hasprefix_cs.
Syntax
T | where Column !hasprefix (Expression)
Learn more about syntax conventions.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
| T | string |
✔️ | The tabular input whose records are to be filtered. |
| Column | string |
✔️ | The column used to filter. |
| Expression | string |
✔️ | The expression for which to search. |
Returns
Rows in T for which the predicate is true.
Example
StormEvents
| summarize event_count=count() by State
| where State !hasprefix "N"
| where event_count > 2000
| project State, event_count
| State | event_count |
|---|---|
| TEXAS | 4701 |
| KANSAS | 3166 |
| IOWA | 2337 |
| ILLINOIS | 2022 |
| MISSOURI | 2016 |