| --- |
| { |
| "title": "CREATE-VIEW", |
| "language": "en" |
| } |
| --- |
| |
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| |
| ## CREATE-VIEW |
| |
| ### Name |
| |
| CREATE VIEW |
| |
| ### Description |
| |
| This statement is used to create a logical view |
| grammar: |
| |
| ```sql |
| CREATE VIEW [IF NOT EXISTS] |
| [db_name.]view_name |
| (column1[ COMMENT "col comment"][, column2, ...]) |
| AS query_stmt |
| ``` |
| |
| |
| illustrate: |
| |
| - Views are logical views and have no physical storage. All queries on the view are equivalent to the sub-queries corresponding to the view. |
| - query_stmt is any supported SQL |
| |
| ### Example |
| |
| 1. Create the view example_view on example_db |
| |
| ```sql |
| CREATE VIEW example_db.example_view (k1, k2, k3, v1) |
| AS |
| SELECT c1 as k1, k2, k3, SUM(v1) FROM example_table |
| WHERE k1 = 20160112 GROUP BY k1,k2,k3; |
| ``` |
| |
| 2. Create a view with a comment |
| |
| ```sql |
| CREATE VIEW example_db.example_view |
| ( |
| k1 COMMENT "first key", |
| k2 COMMENT "second key", |
| k3 COMMENT "third key", |
| v1 COMMENT "first value" |
| ) |
| COMMENT "my first view" |
| AS |
| SELECT c1 as k1, k2, k3, SUM(v1) FROM example_table |
| WHERE k1 = 20160112 GROUP BY k1,k2,k3; |
| ``` |
| |
| ### Keywords |
| |
| CREATE, VIEW |
| |
| ### Best Practice |