dilipbiswal commented on a change in pull request #27216: [SPARK-28588][DOC]
Document SELECT statement in SQL Reference (Main page)
URL: https://github.com/apache/spark/pull/27216#discussion_r367778710
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File path: docs/sql-ref-syntax-qry-select.md
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@@ -18,8 +18,132 @@ license: |
See the License for the specific language governing permissions and
limitations under the License.
---
+Spark supports `SELECT` statement and conforms to ANSI SQL standard. Queries
are
+used to retrieve result sets from one or more table. The following section
+describes the overall query syntax and the sub-sections cover different
constructs
+of a query along with examples.
-Spark SQL is a Apache Spark's module for working with structured data.
-This guide is a reference for Structured Query Language (SQL) for Apache
-Spark. This document describes the SQL constructs supported by Spark in detail
-along with usage examples when applicable.
+### Syntax
+{% highlight sql %}
+[WITH with_query [, ...]]
+SELECT [hints, ...] [ALL|DISTINCT] named_expression[, named_expression, ...]
+ FROM from_item [, from_item, ...]
+ [WHERE boolean_expression]
+ [GROUP BY expression [, ...] ]
+ [HAVING boolean_expression [, ...] ]
+ [ORDER BY expression [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] ]
+ [SORT BY expression [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] ]
+ [CLUSTER BY [expression [, ...] ]
+ [DISTRIBUTE BY [expression [, ...] ]
+ { UNION | INTERSECT | EXCEPT } [ ALL | DISTINCT ] select ]
+ [WINDOW named_window[, WINDOW named_window, ...]]
+ [LIMIT {ALL | expression}]
+{% endhighlight %}
+
+### Parameters
+<dl>
+ <dt><code><em>with_query</em></code></dt>
+ <dd>
+ Specifies the common table expressions (CTEs) before the main
<code>SELECT</code> query block.
+ These table expressions are allowed to be referenced later in the main
query. This is useful to abstract
+ out repeated sub query blocks in the main query and improves readability
of the query.
+ </dd>
+ <dt><code><em>hints</em></code></dt>
+ <dd>
+ Hints can be specified to help spark optimizer make better planning
decisions. Currently spark supports hints
+ that influence selection of join strategies and repartitioning of the
data. For a detailed explanation, please
+ refer to.
Review comment:
@maropu Thanks a lot for reviewing and catching this. I am going to remove
that sentence for now. I wanted to refer to the Hints page from here. I will
add it when i have it ready.
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