ektravel commented on code in PR #15669:
URL: https://github.com/apache/druid/pull/15669#discussion_r1450638934
##########
docs/querying/sql.md:
##########
@@ -85,6 +87,121 @@ FROM clause, metadata tables are not considered
datasources. They exist only in
For more information about table, lookup, query, and join datasources, refer
to the [Datasources](datasource.md)
documentation.
+## PIVOT
+
+:::info
+The PIVOT operator is an [experimental
feature](../development/experimental-features.md).
+:::
+
+The PIVOT operator carries out an aggregation and transforms rows into columns
in the output.
+
+The following is the general syntax for the PIVOT operator. Note that the
PIVOT operator is enclosed in parentheses and forms part of the FORM clause of
the query.
+
+```sql
+PIVOT (aggregation_function(column_to_aggregate)
+ FOR [column_with_values_to_pivot]
+ IN ( [pivoted_column1], [pivoted_column2] ...)
+)
+```
+
+PIVOT syntax parameters:
+
+* `aggregation_function`: An aggregation function such as SUM, COUNT, MIN,
MAX, or AVG.
+* `column_to_aggregate`: The source column to be aggregated.
+* `column_with_values_to_pivot`: The column that contains values for the
pivoted column names.
+* `pivoted_columnN`: The list of values to pivot into headings in the output.
+
+The following example demonstrates how to transform `cityName` values into
column headings `a_sum_deleted` and `b_sum_deleted`:
+
+```sql
+SELECT user, a_sum_deleted, b_sum_deleted
+FROM "wikipedia"
+PIVOT (SUM(deleted) AS "sum_deleted" FOR "cityName" IN ('Buenos Aires' AS b,
'Abu Dhabi' AS a))
+WHERE b_sum_deleted IS NOT NULL OR a_sum_deleted IS NOT NULL
+LIMIT 15
+```
+
+<details>
+<summary> View results </summary>
+
+| `user` | `a_sum_deleted` | `b_sum_deleted`|
+| ------ | --------------- | -------------- |
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|190.123.145.147| null| 0|
+|181.230.118.178| null| 16|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|190.192.179.192| null| 0|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|181.230.118.178| null| 0|
+|86.98.150.78| 0| null|
+
+</details>
+
+## UNPIVOT
+
+:::info
+The UNPIVOT operator is an [experimental
feature](../development/experimental-features.md).
+:::
+
+The UNPIVOT operator transforms existing column values into rows.
+Note that UNPIVOT isn't the exact reverse operation of PIVOT. The PIVOT
operator carries out an aggregation and merges rows as needed. UNPIVOT doesn't
reproduce the original rows that have been merged.
+
+The following is the general syntax for the UNPIVOT operator. Note that the
UNPIVOT operator is enclosed in parentheses and forms part of the FORM clause
of the query.
Review Comment:
Good catch. Fixed.
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