[database-name .] view-name trigger-action
database-event ::=
DELETE | INSERT | UPDATE | UPDATE OF column-list
trigger-action ::=
[ FOR EACH ROW | FOR EACH STATEMENT ] [ WHEN expression ] BEGIN trigger-step ; [ trigger-step ; ]* END
trigger-step ::=
update-statement | insert-statement | delete-statement | select-statement
例子: CREATE TRIGGER update_customer_address UPDATE OF address ON customers BEGIN UPDATE orders SET address = new.address WHERE customer_name = old.name; END; 说明: 创建了一个名为update_customer_address的触发器,当用户更新customers表中的address字段时,将触发并更新orders表中的address字段为新的值。 比如执行如下一条语句: UPDATE customers SET address = ''''1 Main St.'''' WHERE name = ''''Jack Jones''''; 数据库将自动执行如下语句: UPDATE orders SET address = ''''1 Main St.'''' WHERE customer_name = ''''Jack Jones'''';
CREATE INDEX
为给定表或视图创建索引。
语法:
sql-statement ::=
CREATE [UNIQUE] INDEX index-name ON [database-name .] table-name ( column-name [, column-name]* ) [ ON CONFLICT conflict-algorithm ]
column-name ::=
name [ COLLATE collation-name] [ ASC | DESC ]
例子: CREATE INDEX idx_email ON customers (email); 说明: 为customers表中的email创建一个名为idx_email的字段。
结构删除
DROP TABLE
删除表定义及该表的所有索引。
语法:
sql-command ::=
DROP TABLE [database-name.] table-name 例子: DROP TABLE customers;
DROP VIEW
删除一个视图。
语法:
sql-command ::=
DROP VIEW view-name
例子: DROP VIEW master_view;
DROP TRIGGER
删除一个触发器。
语法:
sql-statement ::=
DROP TRIGGER [database-name .] trigger-name
例子: DROP TRIGGER update_customer_address;
DROP INDEX
删除一个索引。
语法:
sql-command ::=
DROP INDEX [database-name .] index-name
例子: DROP INDEX idx_email;
数据操作
INSERT
将新行插入到表。
语法:
sql-statement ::=
INSERT [OR conflict-algorithm] INTO [database-name .] table-name [(column-list)] VALUES(value-list) | INSERT [OR conflict-algorithm] INTO [database-name .] table-name [(column-list)] select-statement
UPDATE
更新表中的现有数据。
语法:
sql-statement ::=
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