SQL to Kusto Query Language cheat sheet

If you're familiar with SQL and want to learn KQL, translate SQL queries into KQL by prefacing the SQL query with a comment line, --, and the keyword explain. The output shows the KQL version of the query, which can help you understand the KQL syntax and concepts.

Run the query

--
explain
SELECT COUNT_BIG(*) as C FROM StormEvents 

Output

Query
StormEvents<br>| summarize C=count()<br>| project C

SQL to Kusto cheat sheet

The following table shows sample queries in SQL and their KQL equivalents.

Category	SQL Query	Kusto Query	Learn more
Select data from table	SELECT * FROM dependencies	dependencies	Tabular expression statements
--	SELECT name, resultCode FROM dependencies	dependencies | project name, resultCode	project
--	SELECT TOP 100 * FROM dependencies	dependencies | take 100	take
Null evaluation	SELECT * FROM dependencies WHERE resultCode IS NOT NULL	dependencies | where isnotnull(resultCode)	isnotnull()
Comparison operators (date)	SELECT * FROM dependencies WHERE timestamp > getdate()-1	dependencies | where timestamp > ago(1d)	ago()
--	SELECT * FROM dependencies WHERE timestamp BETWEEN ... AND ...	dependencies | where timestamp between (datetime(2016-10-01) .. datetime(2016-11-01))	between
Comparison operators (string)	SELECT * FROM dependencies WHERE type = "Azure blob"	dependencies | where type == "Azure blob"	Logical operators
--	-- substring SELECT * FROM dependencies WHERE type like "%blob%"	// substring dependencies | where type contains "blob"	contains
--	-- wildcard SELECT * FROM dependencies WHERE type like "Azure%"	// wildcard dependencies | where type startswith "Azure" // or dependencies | where type matches regex "^Azure.*"	startswith matches regex
Comparison (boolean)	SELECT * FROM dependencies WHERE !(success)	dependencies | where success == False	Logical operators
Grouping, Aggregation	SELECT name, AVG(duration) FROM dependencies GROUP BY name	dependencies | summarize avg(duration) by name	summarize avg()
Distinct	SELECT DISTINCT name, type FROM dependencies	dependencies | summarize by name, type	summarize distinct
--	SELECT name, COUNT(DISTINCT type) FROM dependencies GROUP BY name	dependencies | summarize by name, type | summarize count() by name // or approximate for large sets dependencies | summarize dcount(type) by name	count() dcount()
Column aliases, Extending	SELECT operationName as Name, AVG(duration) as AvgD FROM dependencies GROUP BY name	dependencies | summarize AvgD = avg(duration) by Name=operationName	Alias statement
--	SELECT conference, CONCAT(sessionid, ' ' , session_title) AS session FROM ConferenceSessions	ConferenceSessions | extend session=strcat(sessionid, " ", session_title) | project conference, session	strcat() project
Ordering	SELECT name, timestamp FROM dependencies ORDER BY timestamp ASC	dependencies | project name, timestamp | sort by timestamp asc nulls last	sort
Top n by measure	SELECT TOP 100 name, COUNT(*) as Count FROM dependencies GROUP BY name ORDER BY Count DESC	dependencies | summarize Count = count() by name | top 100 by Count desc	top
Union	SELECT * FROM dependencies UNION SELECT * FROM exceptions	union dependencies, exceptions	union
--	SELECT * FROM dependencies WHERE timestamp > ... UNION SELECT * FROM exceptions WHERE timestamp > ...	dependencies | where timestamp > ago(1d) | union (exceptions | where timestamp > ago(1d))
Join	SELECT * FROM dependencies LEFT OUTER JOIN exceptions ON dependencies.operation_Id = exceptions.operation_Id	dependencies | join kind = leftouter (exceptions) on $left.operation_Id == $right.operation_Id	join
Nested queries	SELECT * FROM dependencies WHERE resultCode == (SELECT TOP 1 resultCode FROM dependencies WHERE resultId = 7 ORDER BY timestamp DESC)	dependencies | where resultCode == toscalar( dependencies | where resultId == 7 | top 1 by timestamp desc | project resultCode)	toscalar
Having	SELECT COUNT(\*) FROM dependencies GROUP BY name HAVING COUNT(\*) > 3	dependencies | summarize Count = count() by name | where Count > 3	summarize where

Next steps

• Use T-SQL to query data