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Posted to commits@spark.apache.org by do...@apache.org on 2021/08/17 19:47:58 UTC

[spark] branch branch-3.2 updated: [SPARK-36535][SQL] Refine the sql reference doc

This is an automated email from the ASF dual-hosted git repository.

dongjoon pushed a commit to branch branch-3.2
in repository https://gitbox.apache.org/repos/asf/spark.git


The following commit(s) were added to refs/heads/branch-3.2 by this push:
     new 5107ad3  [SPARK-36535][SQL] Refine the sql reference doc
5107ad3 is described below

commit 5107ad3157c07c91fec2e30fc97e72684b84cf14
Author: Wenchen Fan <we...@databricks.com>
AuthorDate: Tue Aug 17 12:46:38 2021 -0700

    [SPARK-36535][SQL] Refine the sql reference doc
    
    ### What changes were proposed in this pull request?
    
    Refine the SQL reference doc:
    - remove useless subitems in the sidebar
    - remove useless sub-menu-pages (e.g. `sql-ref-syntax-aux.md`)
    - avoid using `#####` in `sql-ref-literals.md`
    
    ### Why are the changes needed?
    
    The subitems in the sidebar are quite useless, as the menu page serves the same functionalities:
    <img width="1040" alt="WX20210817-2358402x" src="https://user-images.githubusercontent.com/3182036/129765924-d7e69bc1-e351-4581-a6de-f2468022f372.png">
    It's also extra work to keep the manu page and sidebar subitems in sync (The ANSI compliance page is already out of sync).
    
    The sub-menu-pages are only referenced by the sidebar, and duplicates the content of the menu page. As a result, the `sql-ref-syntax-aux.md` is already outdated compared to the menu page. It's easier to just look at the menu page.
    
    The `#####` is not rendered properly:
    <img width="776" alt="WX20210818-0001192x" src="https://user-images.githubusercontent.com/3182036/129766760-6f385443-e597-44aa-888d-14d128d45f84.png">
    It's better to avoid using it.
    
    ### Does this PR introduce _any_ user-facing change?
    
    No
    
    ### How was this patch tested?
    
    N/A
    
    Closes #33767 from cloud-fan/doc.
    
    Authored-by: Wenchen Fan <we...@databricks.com>
    Signed-off-by: Dongjoon Hyun <dh...@apple.com>
    (cherry picked from commit 4b015e8d7d6f5972341104f2a359bb9d09c4385b)
    Signed-off-by: Dongjoon Hyun <dh...@apple.com>
---
 docs/_data/menu-sql.yaml          | 187 +-------------------------------------
 docs/sql-ref-literals.md          |  42 ++++-----
 docs/sql-ref-syntax-aux.md        |  29 ------
 docs/sql-ref-syntax-ddl.md        |  37 --------
 docs/sql-ref-syntax-dml-insert.md |  27 ------
 docs/sql-ref-syntax-dml.md        |  25 -----
 docs/sql-ref-syntax-qry.md        |  53 -----------
 docs/sql-ref-syntax.md            |  12 +++
 8 files changed, 34 insertions(+), 378 deletions(-)

diff --git a/docs/_data/menu-sql.yaml b/docs/_data/menu-sql.yaml
index e7b22c4..22e01df 100644
--- a/docs/_data/menu-sql.yaml
+++ b/docs/_data/menu-sql.yaml
@@ -75,28 +75,12 @@
   subitems:
     - text: ANSI Compliance
       url: sql-ref-ansi-compliance.html
-      subitems:
-        - text: Arithmetic Operations
-          url: sql-ref-ansi-compliance.html#arithmetic-operations
-        - text: Type Conversion
-          url: sql-ref-ansi-compliance.html#type-conversion
-        - text: SQL Keywords
-          url: sql-ref-ansi-compliance.html#sql-keywords
     - text: Data Types
       url: sql-ref-datatypes.html
     - text: Datetime Pattern
       url: sql-ref-datetime-pattern.html
     - text: Functions
       url: sql-ref-functions.html
-      subitems:
-      - text: Built-in Functions
-        url: sql-ref-functions-builtin.html
-      - text: Scalar UDFs (User-Defined Functions)
-        url: sql-ref-functions-udf-scalar.html
-      - text: UDAFs (User-Defined Aggregate Functions)
-        url: sql-ref-functions-udf-aggregate.html
-      - text: Integration with Hive UDFs/UDAFs/UDTFs
-        url: sql-ref-functions-udf-hive.html
     - text: Identifiers
       url: sql-ref-identifier.html
     - text: Literals
@@ -107,173 +91,10 @@
       url: sql-ref-syntax.html
       subitems:
         - text: Data Definition Statements
-          url: sql-ref-syntax-ddl.html
-          subitems:
-            - text: ALTER DATABASE
-              url: sql-ref-syntax-ddl-alter-database.html
-            - text: ALTER TABLE
-              url: sql-ref-syntax-ddl-alter-table.html
-            - text: ALTER VIEW
-              url: sql-ref-syntax-ddl-alter-view.html
-            - text: CREATE DATABASE
-              url: sql-ref-syntax-ddl-create-database.html
-            - text: CREATE FUNCTION
-              url: sql-ref-syntax-ddl-create-function.html
-            - text: CREATE TABLE
-              url: sql-ref-syntax-ddl-create-table.html
-            - text: CREATE VIEW
-              url: sql-ref-syntax-ddl-create-view.html
-            - text: DROP DATABASE
-              url: sql-ref-syntax-ddl-drop-database.html
-            - text: DROP FUNCTION
-              url: sql-ref-syntax-ddl-drop-function.html
-            - text: DROP TABLE
-              url: sql-ref-syntax-ddl-drop-table.html
-            - text: DROP VIEW
-              url: sql-ref-syntax-ddl-drop-view.html
-            - text: TRUNCATE TABLE
-              url: sql-ref-syntax-ddl-truncate-table.html
-            - text: REPAIR TABLE
-              url: sql-ref-syntax-ddl-repair-table.html
-            - text: USE DATABASE
-              url: sql-ref-syntax-ddl-usedb.html
+          url: sql-ref-syntax.html#ddl-statements
         - text: Data Manipulation Statements
-          url: sql-ref-syntax-dml.html
-          subitems:
-            - text: INSERT
-              url: sql-ref-syntax-dml-insert.html
-            - text: LOAD
-              url: sql-ref-syntax-dml-load.html
+          url: sql-ref-syntax.html#dml-statements
         - text: Data Retrieval(Queries)
-          url: sql-ref-syntax-qry.html
-          subitems:
-            - text: SELECT 
-              url: sql-ref-syntax-qry-select.html 
-              subitems:
-                - text: WHERE Clause 
-                  url: sql-ref-syntax-qry-select-where.html
-                - text: GROUP BY Clause 
-                  url: sql-ref-syntax-qry-select-groupby.html
-                - text: HAVING Clause 
-                  url: sql-ref-syntax-qry-select-having.html
-                - text: ORDER BY Clause 
-                  url: sql-ref-syntax-qry-select-orderby.html
-                - text: SORT BY Clause 
-                  url: sql-ref-syntax-qry-select-sortby.html
-                - text: CLUSTER BY Clause 
-                  url: sql-ref-syntax-qry-select-clusterby.html
-                - text: DISTRIBUTE BY Clause 
-                  url: sql-ref-syntax-qry-select-distribute-by.html
-                - text: LIMIT Clause 
-                  url: sql-ref-syntax-qry-select-limit.html
-                - text: Common Table Expression
-                  url: sql-ref-syntax-qry-select-cte.html
-                - text: Hints
-                  url: sql-ref-syntax-qry-select-hints.html
-                - text: Inline Table
-                  url: sql-ref-syntax-qry-select-inline-table.html
-                - text: File
-                  url: sql-ref-syntax-qry-select-file.html
-                - text: JOIN
-                  url: sql-ref-syntax-qry-select-join.html
-                - text: LIKE Predicate
-                  url: sql-ref-syntax-qry-select-like.html
-                - text: Set Operators
-                  url: sql-ref-syntax-qry-select-setops.html
-                - text: TABLESAMPLE
-                  url: sql-ref-syntax-qry-select-sampling.html
-                - text: Table-valued Function
-                  url: sql-ref-syntax-qry-select-tvf.html
-                - text: Window Function
-                  url: sql-ref-syntax-qry-select-window.html
-                - text: CASE Clause
-                  url: sql-ref-syntax-qry-select-case.html
-                - text: LATERAL VIEW Clause
-                  url: sql-ref-syntax-qry-select-lateral-view.html
-                - text: PIVOT Clause
-                  url: sql-ref-syntax-qry-select-pivot.html
-                - text: TRANSFORM Clause
-                  url: sql-ref-syntax-qry-select-transform.html
-            - text: EXPLAIN
-              url: sql-ref-syntax-qry-explain.html
+          url: sql-ref-syntax.html#data-retrieval-statements
         - text: Auxiliary Statements
-          url: sql-ref-syntax-aux.html
-          subitems:
-            - text: ANALYZE
-              url: sql-ref-syntax-aux-analyze.html
-              subitems: 
-                - text: ANALYZE TABLE
-                  url: sql-ref-syntax-aux-analyze-table.html
-                - text: ANALYZE TABLES
-                  url: sql-ref-syntax-aux-analyze-tables.html
-            - text: CACHE
-              url: sql-ref-syntax-aux-cache.html
-              subitems:
-                - text: CACHE TABLE
-                  url: sql-ref-syntax-aux-cache-cache-table.html
-                - text: UNCACHE TABLE
-                  url: sql-ref-syntax-aux-cache-uncache-table.html
-                - text: CLEAR CACHE
-                  url: sql-ref-syntax-aux-cache-clear-cache.html
-                - text: REFRESH TABLE
-                  url: sql-ref-syntax-aux-cache-refresh-table.html
-                - text: REFRESH FUNCTION
-                  url: sql-ref-syntax-aux-cache-refresh-function.html
-                - text: REFRESH
-                  url: sql-ref-syntax-aux-cache-refresh.html
-            - text: DESCRIBE
-              url: sql-ref-syntax-aux-describe.html
-              subitems:
-                - text: DESCRIBE DATABASE
-                  url: sql-ref-syntax-aux-describe-database.html
-                - text: DESCRIBE TABLE
-                  url: sql-ref-syntax-aux-describe-table.html
-                - text: DESCRIBE FUNCTION
-                  url: sql-ref-syntax-aux-describe-function.html
-                - text: DESCRIBE QUERY
-                  url: sql-ref-syntax-aux-describe-query.html
-            - text: SHOW
-              url: sql-ref-syntax-aux-show.html
-              subitems:
-                - text: SHOW COLUMNS 
-                  url: sql-ref-syntax-aux-show-columns.html
-                - text: SHOW CREATE TABLE
-                  url: sql-ref-syntax-aux-show-create-table.html
-                - text: SHOW DATABASES
-                  url: sql-ref-syntax-aux-show-databases.html
-                - text: SHOW FUNCTIONS
-                  url: sql-ref-syntax-aux-show-functions.html
-                - text: SHOW PARTITIONS
-                  url: sql-ref-syntax-aux-show-partitions.html
-                - text: SHOW TABLE
-                  url: sql-ref-syntax-aux-show-table.html
-                - text: SHOW TABLES
-                  url: sql-ref-syntax-aux-show-tables.html
-                - text: SHOW TBLPROPERTIES
-                  url: sql-ref-syntax-aux-show-tblproperties.html
-                - text: SHOW VIEWS
-                  url: sql-ref-syntax-aux-show-views.html
-            - text: CONFIGURATION MANAGEMENT
-              url: sql-ref-syntax-aux-conf-mgmt.html
-              subitems:
-                - text: SET 
-                  url: sql-ref-syntax-aux-conf-mgmt-set.html
-                - text: RESET
-                  url: sql-ref-syntax-aux-conf-mgmt-reset.html
-                - text: SET TIME ZONE
-                  url: sql-ref-syntax-aux-conf-mgmt-set-timezone.html
-            - text: RESOURCE MANAGEMENT
-              url: sql-ref-syntax-aux-resource-mgmt.html
-              subitems:
-                - text: ADD FILE
-                  url: sql-ref-syntax-aux-resource-mgmt-add-file.html
-                - text: ADD JAR
-                  url: sql-ref-syntax-aux-resource-mgmt-add-jar.html
-                - text: ADD ARCHIVE
-                  url: sql-ref-syntax-aux-resource-mgmt-add-archive.html
-                - text: LIST FILE
-                  url: sql-ref-syntax-aux-resource-mgmt-list-file.html
-                - text: LIST JAR
-                  url: sql-ref-syntax-aux-resource-mgmt-list-jar.html
-                - text: LIST ARCHIVE
-                  url: sql-ref-syntax-aux-resource-mgmt-list-archive.html
+          url: sql-ref-syntax.html#auxiliary-statements
diff --git a/docs/sql-ref-literals.md b/docs/sql-ref-literals.md
index 355ac69..7a81d36 100644
--- a/docs/sql-ref-literals.md
+++ b/docs/sql-ref-literals.md
@@ -144,16 +144,15 @@ SELECT TRUE AS col;
 ### Numeric Literal
 
 A numeric literal is used to specify a fixed or floating-point number.
+There are two kinds of numeric literals: integral literal and fractional literal.
 
-#### Integral Literal
-
-##### Syntax
+#### Integral Literal Syntax
 
 ```sql
 [ + | - ] digit [ ... ] [ L | S | Y ]
 ```
 
-##### Parameters
+#### Integral Literal Parameters
 
 * **digit**
 
@@ -175,7 +174,7 @@ A numeric literal is used to specify a fixed or floating-point number.
 
     Indicates a 4-byte signed integer number.
 
-##### Examples
+#### Integral Literal Examples
 
 ```sql
 SELECT -2147483648 AS col;
@@ -207,9 +206,7 @@ SELECT 482S AS col;
 +---+
 ```
 
-#### Fractional Literals
-
-##### Syntax
+#### Fractional Literals Syntax
 
 decimal literals:
 ```sql
@@ -236,7 +233,7 @@ and exponent is defined as
 E [ + | - ] digit [ ... ]
 ```
 
-##### Parameters
+#### Fractional Literals Parameters
 
 * **digit**
 
@@ -254,7 +251,7 @@ E [ + | - ] digit [ ... ]
 
     Case insensitive, indicates `DECIMAL`, with the total number of digits as precision and the number of digits to right of decimal point as scale.
 
-##### Examples
+#### Fractional Literals Examples
 
 ```sql
 SELECT 12.578 AS col;
@@ -344,11 +341,9 @@ SELECT -3.E-3D AS col;
 
 ### Datetime Literal
 
-A Datetime literal is used to specify a datetime value.
+A datetime literal is used to specify a date or timestamp value.
 
-#### Date Literal
-
-##### Syntax
+#### Date Syntax
 
 ```sql
 DATE { 'yyyy' |
@@ -358,7 +353,7 @@ DATE { 'yyyy' |
 ```
 **Note:** defaults to `01` if month or day is not specified.
 
-##### Examples
+#### Date Examples
 
 ```sql
 SELECT DATE '1997' AS col;
@@ -383,9 +378,7 @@ SELECT DATE '2011-11-11' AS col;
 +----------+
 ```
 
-#### Timestamp Literal
-
-##### Syntax
+#### Timestamp Syntax
 
 ```sql
 TIMESTAMP { 'yyyy' |
@@ -410,7 +403,7 @@ TIMESTAMP { 'yyyy' |
 
 **Note:** defaults to the session local timezone (set via `spark.sql.session.timeZone`) if `zone_id` is not specified.
 
-##### Examples
+#### Timestamp Examples
 
 ```sql
 SELECT TIMESTAMP '1997-01-31 09:26:56.123' AS col;
@@ -438,8 +431,9 @@ SELECT TIMESTAMP '1997-01' AS col;
 ### Interval Literal
 
 An interval literal is used to specify a fixed period of time.
+The interval literal supports two syntaxes: ANSI syntax and multi-units syntax.
 
-#### ANSI style
+#### ANSI Syntax
 
 The ANSI SQL standard defines interval literals in the form:
 ```sql
@@ -485,7 +479,7 @@ Formats of supported day-time interval literals:
 |MINUTE TO SECOND|`[+|-]'[+|-]m:s.n'`|`INTERVAL '1000:01.001' MINUTE TO SECOND`|
 |SECOND|`[+|-]'[+|-]s.n'`|`INTERVAL '1000.000001' SECOND`|
 
-##### Examples
+#### ANSI Examples
 
 ```sql
 SELECT INTERVAL '2-3' YEAR TO MONTH AS col;
@@ -503,14 +497,14 @@ SELECT INTERVAL -'20 15:40:32.99899999' DAY TO SECOND AS col;
 +--------------------------------------------+
 ```
 
-#### Multi-units style
+#### Multi-units Syntax
 
 ```sql
 INTERVAL interval_value interval_unit [ interval_value interval_unit ... ] |
 INTERVAL 'interval_value interval_unit [ interval_value interval_unit ... ]' |
 ```
 
-##### Parameters
+#### Multi-units Parameters
 
 * **interval_value**
 
@@ -527,7 +521,7 @@ INTERVAL 'interval_value interval_unit [ interval_value interval_unit ... ]' |
 
       Mix of the YEAR[S] or MONTH[S] interval units with other units is not allowed.
 
-##### Examples
+#### Multi-units Examples
 
 ```sql
 SELECT INTERVAL 3 YEAR AS col;
diff --git a/docs/sql-ref-syntax-aux.md b/docs/sql-ref-syntax-aux.md
deleted file mode 100644
index 3cd758f..0000000
--- a/docs/sql-ref-syntax-aux.md
+++ /dev/null
@@ -1,29 +0,0 @@
----
-layout: global
-title: Auxiliary Statements
-displayTitle: Auxiliary Statements
-license: |
-  Licensed to the Apache Software Foundation (ASF) under one or more
-  contributor license agreements.  See the NOTICE file distributed with
-  this work for additional information regarding copyright ownership.
-  The ASF licenses this file to You under the Apache License, Version 2.0
-  (the "License"); you may not use this file except in compliance with
-  the License.  You may obtain a copy of the License at
- 
-     http://www.apache.org/licenses/LICENSE-2.0
- 
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
----
-
-Besides the major SQL statements such as Data Definition Statements, Data Manipulation Statements and Data Retrieval Statements, Spark SQL also supports the following Auxiliary Statements:
-
- * [ANALYZE](sql-ref-syntax-aux-analyze.html)
- * [CACHE](sql-ref-syntax-aux-cache.html)
- * [DESCRIBE](sql-ref-syntax-aux-describe.html)
- * [SHOW](sql-ref-syntax-aux-show.html)
- * [CONFIGURATION MANAGEMENT](sql-ref-syntax-aux-conf-mgmt.html)
- * [RESOURCE MANAGEMENT](sql-ref-syntax-aux-resource-mgmt.html)
diff --git a/docs/sql-ref-syntax-ddl.md b/docs/sql-ref-syntax-ddl.md
deleted file mode 100644
index cb3e04c..0000000
--- a/docs/sql-ref-syntax-ddl.md
+++ /dev/null
@@ -1,37 +0,0 @@
----
-layout: global
-title: Data Definition Statements
-displayTitle: Data Definition Statements
-license: |
-  Licensed to the Apache Software Foundation (ASF) under one or more
-  contributor license agreements.  See the NOTICE file distributed with
-  this work for additional information regarding copyright ownership.
-  The ASF licenses this file to You under the Apache License, Version 2.0
-  (the "License"); you may not use this file except in compliance with
-  the License.  You may obtain a copy of the License at
- 
-     http://www.apache.org/licenses/LICENSE-2.0
- 
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
----
-
-Data Definition Statements are used to create or modify the structure of database objects in a database. Spark SQL supports the following Data Definition Statements:
-
- * [ALTER DATABASE](sql-ref-syntax-ddl-alter-database.html)
- * [ALTER TABLE](sql-ref-syntax-ddl-alter-table.html)
- * [ALTER VIEW](sql-ref-syntax-ddl-alter-view.html)
- * [CREATE DATABASE](sql-ref-syntax-ddl-create-database.html)
- * [CREATE FUNCTION](sql-ref-syntax-ddl-create-function.html)
- * [CREATE TABLE](sql-ref-syntax-ddl-create-table.html)
- * [CREATE VIEW](sql-ref-syntax-ddl-create-view.html)
- * [DROP DATABASE](sql-ref-syntax-ddl-drop-database.html)
- * [DROP FUNCTION](sql-ref-syntax-ddl-drop-function.html)
- * [DROP TABLE](sql-ref-syntax-ddl-drop-table.html)
- * [DROP VIEW](sql-ref-syntax-ddl-drop-view.html)
- * [TRUNCATE TABLE](sql-ref-syntax-ddl-truncate-table.html)
- * [REPAIR TABLE](sql-ref-syntax-ddl-repair-table.html)
- * [USE DATABASE](sql-ref-syntax-ddl-usedb.html)
diff --git a/docs/sql-ref-syntax-dml-insert.md b/docs/sql-ref-syntax-dml-insert.md
deleted file mode 100644
index 62f6dee..0000000
--- a/docs/sql-ref-syntax-dml-insert.md
+++ /dev/null
@@ -1,27 +0,0 @@
----
-layout: global
-title: INSERT
-displayTitle: INSERT
-license: |
-  Licensed to the Apache Software Foundation (ASF) under one or more
-  contributor license agreements.  See the NOTICE file distributed with
-  this work for additional information regarding copyright ownership.
-  The ASF licenses this file to You under the Apache License, Version 2.0
-  (the "License"); you may not use this file except in compliance with
-  the License.  You may obtain a copy of the License at
-
-     http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
----
-
-The INSERT statements:
-
-* [INSERT INTO statement](sql-ref-syntax-dml-insert-into.html)
-* [INSERT OVERWRITE statement](sql-ref-syntax-dml-insert-overwrite-table.html)
-* [INSERT OVERWRITE DIRECTORY statement](sql-ref-syntax-dml-insert-overwrite-directory.html)
-* [INSERT OVERWRITE DIRECTORY with Hive format statement](sql-ref-syntax-dml-insert-overwrite-directory-hive.html)
diff --git a/docs/sql-ref-syntax-dml.md b/docs/sql-ref-syntax-dml.md
deleted file mode 100644
index fc408e1..0000000
--- a/docs/sql-ref-syntax-dml.md
+++ /dev/null
@@ -1,25 +0,0 @@
----
-layout: global
-title: Data Manipulation Statements
-displayTitle: Data Manipulation Statements
-license: |
-  Licensed to the Apache Software Foundation (ASF) under one or more
-  contributor license agreements.  See the NOTICE file distributed with
-  this work for additional information regarding copyright ownership.
-  The ASF licenses this file to You under the Apache License, Version 2.0
-  (the "License"); you may not use this file except in compliance with
-  the License.  You may obtain a copy of the License at
- 
-     http://www.apache.org/licenses/LICENSE-2.0
- 
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
----
-
-Data Manipulation Statements are used to add, change, or delete data. Spark SQL supports the following Data Manipulation Statements:
-
-* [INSERT](sql-ref-syntax-dml-insert.html)
-* [LOAD](sql-ref-syntax-dml-load.html)
diff --git a/docs/sql-ref-syntax-qry.md b/docs/sql-ref-syntax-qry.md
deleted file mode 100644
index 9fb62df..0000000
--- a/docs/sql-ref-syntax-qry.md
+++ /dev/null
@@ -1,53 +0,0 @@
----
-layout: global
-title: Data Retrieval
-displayTitle: Data Retrieval
-license: |
-  Licensed to the Apache Software Foundation (ASF) under one or more
-  contributor license agreements.  See the NOTICE file distributed with
-  this work for additional information regarding copyright ownership.
-  The ASF licenses this file to You under the Apache License, Version 2.0
-  (the "License"); you may not use this file except in compliance with
-  the License.  You may obtain a copy of the License at
-
-     http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
----
-
-Spark supports <code>SELECT</code> statement that is used to retrieve rows
-from one or more tables according to the specified clauses. The full syntax
-and brief description of supported clauses are explained in
-[SELECT](sql-ref-syntax-qry-select.html) section. The SQL statements related
-to SELECT are also included in this section. Spark also provides the
-ability to generate logical and physical plan for a given query using
-[EXPLAIN](sql-ref-syntax-qry-explain.html) statement.
-
-* [SELECT Statement](sql-ref-syntax-qry-select.html)
-  * [WHERE Clause](sql-ref-syntax-qry-select-where.html)
-  * [GROUP BY Clause](sql-ref-syntax-qry-select-groupby.html)
-  * [HAVING Clause](sql-ref-syntax-qry-select-having.html)
-  * [ORDER BY Clause](sql-ref-syntax-qry-select-orderby.html)
-  * [SORT BY Clause](sql-ref-syntax-qry-select-sortby.html)
-  * [CLUSTER BY Clause](sql-ref-syntax-qry-select-clusterby.html)
-  * [DISTRIBUTE BY Clause](sql-ref-syntax-qry-select-distribute-by.html)
-  * [LIMIT Clause](sql-ref-syntax-qry-select-limit.html)
-  * [Common Table Expression](sql-ref-syntax-qry-select-cte.html)
-  * [Hints](sql-ref-syntax-qry-select-hints.html)
-  * [Inline Table](sql-ref-syntax-qry-select-inline-table.html)
-  * [File](sql-ref-syntax-qry-select-file.html)
-  * [JOIN](sql-ref-syntax-qry-select-join.html)
-  * [LIKE Predicate](sql-ref-syntax-qry-select-like.html)
-  * [Set Operators](sql-ref-syntax-qry-select-setops.html)
-  * [TABLESAMPLE](sql-ref-syntax-qry-select-sampling.html)
-  * [Table-valued Function](sql-ref-syntax-qry-select-tvf.html)
-  * [Window Function](sql-ref-syntax-qry-select-window.html)
-  * [CASE Clause](sql-ref-syntax-qry-select-case.html)
-  * [PIVOT Clause](sql-ref-syntax-qry-select-pivot.html)
-  * [LATERAL VIEW Clause](sql-ref-syntax-qry-select-lateral-view.html)
-  * [TRANSFORM Clause](sql-ref-syntax-qry-select-transform.html)
-* [EXPLAIN Statement](sql-ref-syntax-qry-explain.html)
diff --git a/docs/sql-ref-syntax.md b/docs/sql-ref-syntax.md
index f02b1ac..cb7a04d 100644
--- a/docs/sql-ref-syntax.md
+++ b/docs/sql-ref-syntax.md
@@ -23,6 +23,8 @@ Spark SQL is Apache Spark's module for working with structured data. The SQL Syn
 
 ### DDL Statements
 
+Data Definition Statements are used to create or modify the structure of database objects in a database. Spark SQL supports the following Data Definition Statements:
+
  * [ALTER DATABASE](sql-ref-syntax-ddl-alter-database.html)
  * [ALTER TABLE](sql-ref-syntax-ddl-alter-table.html)
  * [ALTER VIEW](sql-ref-syntax-ddl-alter-view.html)
@@ -40,6 +42,8 @@ Spark SQL is Apache Spark's module for working with structured data. The SQL Syn
 
 ### DML Statements
 
+Data Manipulation Statements are used to add, change, or delete data. Spark SQL supports the following Data Manipulation Statements:
+
  * [INSERT INTO](sql-ref-syntax-dml-insert-into.html)
  * [INSERT OVERWRITE](sql-ref-syntax-dml-insert-overwrite-table.html)
  * [INSERT OVERWRITE DIRECTORY](sql-ref-syntax-dml-insert-overwrite-directory.html)
@@ -48,6 +52,14 @@ Spark SQL is Apache Spark's module for working with structured data. The SQL Syn
 
 ### Data Retrieval Statements
 
+Spark supports <code>SELECT</code> statement that is used to retrieve rows
+from one or more tables according to the specified clauses. The full syntax
+and brief description of supported clauses are explained in
+[SELECT](sql-ref-syntax-qry-select.html) section. The SQL statements related
+to SELECT are also included in this section. Spark also provides the
+ability to generate logical and physical plan for a given query using
+[EXPLAIN](sql-ref-syntax-qry-explain.html) statement.
+
  * [SELECT Statement](sql-ref-syntax-qry-select.html)
    * [Common Table Expression](sql-ref-syntax-qry-select-cte.html)
    * [CLUSTER BY Clause](sql-ref-syntax-qry-select-clusterby.html)

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