CREATE VIEW
The CREATE VIEW
statement saves a SELECT
statement as a queryable object, similar to a table. Views in TiDB are non-materialized. This means that as a view is queried, TiDB will internally rewrite the query to combine the view definition with the SQL query.
Synopsis
- CreateViewStmt
- OrReplace
- ViewAlgorithm
- ViewDefiner
- ViewSQLSecurity
- ViewName
- ViewFieldList
- ViewCheckOption
CreateViewStmt ::=
'CREATE' OrReplace ViewAlgorithm ViewDefiner ViewSQLSecurity 'VIEW' ViewName ViewFieldList 'AS' CreateViewSelectOpt ViewCheckOption
OrReplace ::=
( 'OR' 'REPLACE' )?
ViewAlgorithm ::=
( 'ALGORITHM' '=' ( 'UNDEFINED' | 'MERGE' | 'TEMPTABLE' ) )?
ViewDefiner ::=
( 'DEFINER' '=' Username )?
ViewSQLSecurity ::=
( 'SQL' 'SECURITY' ( 'DEFINER' | 'INVOKER' ) )?
ViewName ::= TableName
ViewFieldList ::=
( '(' Identifier ( ',' Identifier )* ')' )?
ViewCheckOption ::=
( 'WITH' ( 'CASCADED' | 'LOCAL' ) 'CHECK' 'OPTION' )?
Examples
mysql> CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, c1 INT NOT NULL);
Query OK, 0 rows affected (0.11 sec)
mysql> INSERT INTO t1 (c1) VALUES (1),(2),(3),(4),(5);
Query OK, 5 rows affected (0.03 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> CREATE VIEW v1 AS SELECT * FROM t1 WHERE c1 > 2;
Query OK, 0 rows affected (0.11 sec)
mysql> SELECT * FROM t1;
+----+----+
| id | c1 |
+----+----+
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
+----+----+
5 rows in set (0.00 sec)
mysql> SELECT * FROM v1;
+----+----+
| id | c1 |
+----+----+
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
+----+----+
3 rows in set (0.00 sec)
mysql> INSERT INTO t1 (c1) VALUES (6);
Query OK, 1 row affected (0.01 sec)
mysql> SELECT * FROM v1;
+----+----+
| id | c1 |
+----+----+
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
| 6 | 6 |
+----+----+
4 rows in set (0.00 sec)
mysql> INSERT INTO v1 (c1) VALUES (7);
ERROR 1105 (HY000): insert into view v1 is not supported now.
MySQL compatibility
- Currently, any view in TiDB cannot be inserted or updated (that is,
INSERT VIEW
andUPDATE VIEW
are not supported).WITH CHECK OPTION
is only syntactically compatible but does not take effect. - Currently, the view in TiDB does not support
ALTER VIEW
, but you can useCREATE OR REPLACE
instead. - Currently, the
ALGORITHM
field is only syntactically compatible in TiDB but does not take effect. TiDB currently only supports the MERGE algorithm.