[SPARK-28791] [DOC] Documentation for Alter table Command

docs/sql-ref-syntax-ddl-alter-table.md

@@ -19,4 +19,240 @@ license: |
   limitations under the License.
 ---
 
-**This page is under construction**
+### Description
+`ALTER TABLE` statement changes the schema or properties of a table.
+
+### RENAME 
+`ALTER TABLE RENAME` statement changes the table name of an existing table in the database.
+
+#### Syntax
+{% highlight sql %}
+ALTER TABLE [db_name.]old_table_name RENAME TO [db_name.]new_table_name
+
+ALTER TABLE table_name PARTITION partition_spec RENAME TO PARTITION partition_spec;
+
+{% endhighlight %}
+
+#### Parameters
+<dl>
+  <dt><code><em>old_table_name</em></code></dt>
+  <dd>Name of an existing table.</dd>
+</dl>
+<dl>
+  <dt><code><em>db_name</em></code></dt>
+  <dd>Name of the existing database.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>new_table_name</em></code></dt>
+  <dd>New name using which the table has to be renamed.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>partition_spec</em></code></dt>
+  <dd>Partition to be renamed.</dd>
+</dl>
+
+
+### ADD COLUMNS
+`ALTER TABLE ADD COLUMNS` statement adds mentioned columns to an existing table.
+
+#### Syntax
+{% highlight sql %}
+ALTER TABLE table_name ADD COLUMNS (col_spec[, col_spec ...])
+{% endhighlight %}
+
+#### Parameters
+<dl>
+  <dt><code><em>table_name</em></code></dt>
+  <dd>The name of an existing table.</dd>
+</dl>
+
+
+<dl>
+  <dt><code><em>COLUMNS (col_spec)</em></code></dt>
+  <dd>Specifies the columns to be added to be renamed.</dd>
+</dl>
+
+
+### SET AND UNSET
+
+#### SET TABLE PROPERTIES
+`ALTER TABLE SET` command is used for setting the table properties. If a particular property was already set, 
+this overrides the old value with the new one.
+
+`ALTER TABLE UNSET` is used to drop the table property. 
+
+##### Syntax
+{% highlight sql %}
+
+--Set Table Properties 
+ALTER TABLE table_name SET TBLPROPERTIES (key1=val1, key2=val2, ...)
+
+--Unset Table Properties
+ALTER TABLE table_name UNSET TBLPROPERTIES [IF EXISTS] (key1, key2, ...)
+
+{% endhighlight %}
+
+#### SET SERDE
+`ALTER TABLE SET` command is used for setting the SERDE or SERDE properties in Hive tables. If a particular property was already set,  
+this overrides the old value with the new one.
+
+##### Syntax
+{% highlight sql %}
+
+--Set SERDE Propeties
+ALTER TABLE table_name [PARTITION part_spec]
+    SET SERDEPROPERTIES (key1=val1, key2=val2, ...)
+
+ALTER TABLE table_name [PARTITION part_spec] SET SERDE serde_class_name
+    [WITH SERDEPROPERTIES (key1=val1, key2=val2, ...)]
+
+{% endhighlight %}
+
+#### SET LOCATION And SET FILE FORMAT
+`ALTER TABLE SET` command can also be used for changing the file location and file format for 
+exsisting tables. 
+
+##### Syntax
+{% highlight sql %}
+
+--Changing File Format
+ALTER TABLE table_name [PARTITION partition_spec] SET FILEFORMAT file_format;
+
+--Changing File Location
+ALTER TABLE table_name [PARTITION partition_spec] SET LOCATION 'new_location';
+
+{% endhighlight %}
+
+#### Parameters
+<dl>
+  <dt><code><em>table_name</em></code></dt>
+  <dd>The name of an existing table.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>PARTITION (part_spec)</em></code></dt>
+  <dd>Specifies the partition on which the property has to be set.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>SERDEPROPERTIES (key1=val1, key2=val2, ...)</em></code></dt>
+  <dd>Specifies the SERDE properties to be set.</dd>
+</dl>
+
+
+### Examples
+{% highlight sql %}
+
+--RENAME table 
+DESC student;
++--------------------------+------------+----------+--+
+|         col_name         | data_type  | comment  |
++--------------------------+------------+----------+--+
+| name                     | string     | NULL     |
+| rollno                   | int        | NULL     |
+| age                      | int        | NULL     |
+| # Partition Information  |            |          |
+| # col_name               | data_type  | comment  |
+| age                      | int        | NULL     |
++--------------------------+------------+----------+--+
+
+ALTER TABLE Student RENAME TO StudentInfo;
+
+--After Renaming the table
+
+DESC StudentInfo;
++--------------------------+------------+----------+--+
+|         col_name         | data_type  | comment  |
++--------------------------+------------+----------+--+
+| name                     | string     | NULL     |
+| rollno                   | int        | NULL     |
+| age                      | int        | NULL     |
+| # Partition Information  |            |          |
+| # col_name               | data_type  | comment  |
+| age                      | int        | NULL     |
++--------------------------+------------+----------+--+
+
+--RENAME partition
+
+SHOW PARTITIONS StudentInfo;
++------------+--+
+| partition  |
++------------+--+
+| age=10     |
+| age=11     |
+| age=12     |
++------------+--+
+
+ALTER TABLE default.StudentInfo PARTITION (age='10') RENAME TO PARTITION (age='15');
+
+--After renaming Partition
+SHOW PARTITIONS StudentInfo;
++------------+--+
+| partition  |
++------------+--+
+| age=11     |
+| age=12     |
+| age=15     |
++------------+--+
+
+-- Add new column to a table
+
+DESC StudentInfo;
++--------------------------+------------+----------+--+
+|         col_name         | data_type  | comment  |
++--------------------------+------------+----------+--+
+| name                     | string     | NULL     |
+| rollno                   | int        | NULL     |
+| age                      | int        | NULL     |
+| # Partition Information  |            |          |
+| # col_name               | data_type  | comment  |
+| age                      | int        | NULL     |
++--------------------------+------------+----------+
+
+ALTER TABLE StudentInfo ADD columns (LastName string, DOB timestamp);
+
+--After Adding New columns to the table
+DESC StudentInfo;
++--------------------------+------------+----------+--+
+|         col_name         | data_type  | comment  |
++--------------------------+------------+----------+--+
+| name                     | string     | NULL     |
+| rollno                   | int        | NULL     |
+| LastName                 | string     | NULL     |
+| DOB                      | timestamp  | NULL     |
+| age                      | int        | NULL     |
+| # Partition Information  |            |          |
+| # col_name               | data_type  | comment  |
+| age                      | int        | NULL     |
++--------------------------+------------+----------+--+
+
+
+--Change the fileformat
+ALTER TABLE loc_orc SET fileformat orc;
+
+ALTER TABLE p1 partition (month=2, day=2) SET fileformat parquet;
+
+--Change the file Location
+ALTER TABLE dbx.tab1 PARTITION (a='1', b='2') SET LOCATION '/path/to/part/ways'
+
+-- SET SERDE/ SERDE Properties
+ALTER TABLE test_tab SET SERDE 'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe';
+
+ALTER TABLE dbx.tab1 SET SERDE 'org.apache.madoop' WITH SERDEPROPERTIES ('k' = 'v', 'kay' = 'vee')
+
+--SET TABLE PROPERTIES
+ALTER TABLE dbx.tab1 SET TBLPROPERTIES ('winner' = 'loser')
+
+--DROP TABLE PROPERTIES
+ALTER TABLE dbx.tab1 UNSET TBLPROPERTIES ('winner')
+
+{% endhighlight %}
+
+
+### Related Statements
+- [CREATE TABLE](sql-ref-syntax-ddl-create-table.html)
+- [DROP TABLE](sql-ref-syntax-ddl-drop-table.html)
+
+