T-SQL

The query editor supports the use of T-SQL in addition to its primary query language, Kusto query language (KQL). While KQL is the recommended query language, T-SQL can be useful for tools that are unable to use KQL.

Query with T-SQL

To run a T-SQL query, begin the query with an empty T-SQL comment line: --. The -- syntax tells the query editor to interpret the following query as T-SQL and not KQL.

Example

--
SELECT * FROM StormEvents

T-SQL to Kusto Query Language

The query editor supports the ability to translate T-SQL queries into KQL. This translation feature can be helpful for users who are familiar with SQL and want to learn more about KQL.

To get the equivalent KQL for a T-SQL SELECT statement, add the keyword explain before the query. The output will be the KQL version of the query, which can be useful for understanding the corresponding KQL syntax and concepts.

Remember to preface T-SQL queries with a T-SQL comment line, --, to tell the query editor to interpret the following query as T-SQL and not KQL.

Example

--
explain
SELECT top(10) *
FROM StormEvents
ORDER BY DamageProperty DESC

Output

StormEvents
| project
    StartTime,
    EndTime,
    EpisodeId,
    EventId,
    State,
    EventType,
    InjuriesDirect,
    InjuriesIndirect,
    DeathsDirect,
    DeathsIndirect,
    DamageProperty,
    DamageCrops,
    Source,
    BeginLocation,
    EndLocation,
    BeginLat,
    BeginLon,
    EndLat,
    EndLon,
    EpisodeNarrative,
    EventNarrative,
    StormSummary
| sort by DamageProperty desc nulls first
| take int(10)

Run stored functions

When using T-SQL, we recommend that you create optimized KQL queries and encapsulate them in stored functions, as doing so minimizes T-SQL code and may increase performance. For example, if you have a stored function as described in the following table, you can execute it as shown in the code example.

SELECT * FROM kusto.MyFunction(10)

Set request properties

Request properties control how a query executes and returns results. To set request properties with T-SQL, preface your query with one or more statements with the following syntax:

Syntax

DECLARE @__kql_set_requestPropertyName type = value;

Parameters

Examples

The following table shows examples for how to set request properties with T-SQL.

To set request properties with KQL, see set statement.

Coverage

The query environment offers limited support for T-SQL. The following table outlines the T-SQL statements and features that aren’t supported or are partially supported.

Related content

• Learn about SQL Server emulation in Azure Data Explorer
• Use the SQL to Kusto Query Language cheat sheet