huaxingao commented on a change in pull request #35239:
URL: https://github.com/apache/spark/pull/35239#discussion_r793256119
##########
File path: docs/sql-ref-syntax-ddl-alter-table.md
##########
@@ -309,6 +393,116 @@ DESC StudentInfo;
| age| int| NULL|
+-----------------------+---------+-------+
+-- Drop columns of a 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|
++-----------------------+---------+-------+
+
+ALTER TABLE StudentInfo DROP columns (LastName, DOB);
+
+-- After dropping columns of 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 a column of 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 RENAME COLUMN name TO FirstName;
+
+-- After renaming a column of the table
+DESC StudentInfo;
++-----------------------+---------+-------+
+| col_name|data_type|comment|
++-----------------------+---------+-------+
+| FirstName| string| NULL|
+| rollno| int| NULL|
+| age| int| NULL|
+|# Partition Information| | |
+| # col_name|data_type|comment|
+| age| int| NULL|
++-----------------------+---------+-------+
+
+-- ALTER OR CHANGE COLUMNS
+DESC StudentInfo;
++-----------------------+---------+-------+
+| col_name|data_type|comment|
++-----------------------+---------+-------+
+| FirstName| string| NULL|
+| rollno| int| NULL|
+| age| int| NULL|
+|# Partition Information| | |
+| # col_name|data_type|comment|
+| age| int| NULL|
++-----------------------+---------+-------+
+
+ALTER TABLE StudentInfo ALTER COLUMN FirstName COMMENT "new comment";
+
+--After ALTER or CHANGE COLUMNS
+DESC StudentInfo;
++-----------------------+---------+-----------+
+| col_name|data_type| comment|
++-----------------------+---------+-----------+
+| FirstName| string|new comment|
+| rollno| int| NULL|
+| age| int| NULL|
+|# Partition Information| | |
+| # col_name|data_type| comment|
+| age| int| NULL|
++-----------------------+---------+-----------+
+
+-- REPLACE COLUMNS
+DESC StudentInfo;
++-----------------------+---------+-----------+
+| col_name|data_type| comment|
++-----------------------+---------+-----------+
+| FirstName| string|new comment|
+| rollno| int| NULL|
+| age| int| NULL|
+|# Partition Information| | |
+| # col_name|data_type| comment|
+| age| int| NULL|
++-----------------------+---------+-----------+
+
+ALTER TABLE StudentInfo REPLACE COLUMNS (name string, ID int COMMENT 'new
comment');
+
+--After replacing COLUMNS
Review comment:
nit: space after `-`
##########
File path: docs/sql-ref-syntax-ddl-alter-table.md
##########
@@ -435,6 +597,9 @@ ALTER TABLE dbx.tab1 SET TBLPROPERTIES ('comment' = 'This
is a new comment.');
-- DROP TABLE PROPERTIES
ALTER TABLE dbx.tab1 UNSET TBLPROPERTIES ('winner');
+
+-- RECOVER PARTITIONS
+ALTER TABLE dbx.tab1 RECOVER PARTITIONS
Review comment:
nit: `;` in the end
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