SQL to Kusto Query Language cheat sheet

  • Article
  • 10/08/2024

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

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 has "blob"		 has
-- -- 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

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