In this tutorial, you will learn how to use the CREATE TRIGGER statement to create a new statement-level trigger in the database.
3、BEFORE和AFTER触发器： 分别在操作执行前后触发。A trigger in Oracle database is a special type of stored procedure that automatically executes when a specific database operation occurs. Types of triggers include:Row-level Trigger: This trigger fires when a single row is modified.Statement-level ...
condition是可选的 ORACLE BOOLEAN条件,当条件为真时触发器触发; trigger_body是触发器触发时执行的PL/SQL块。 (2)、ORACLE触发器有以下两类: 1> 语句级(Statement-level)触发器,在CREATE TRIGGER语句中不包含FOR EACH ROW子句。语句级触发器对于触发事件只能触发一次, 而且不能访问受触发器影响的每一行的列值。...
postgres=# explain plan for select * from test;EXPLAIN SUCCESSpostgres=# SELECT * FROM PLAN_TABLE; statement_id | plan_id | id | operation | options | object_name | object_type | object_owner | projection ---+---+---+---+---+---+---+---+--- | 28147497671086...
The clauseFOR EACH ROWspecifies that the trigger is arow-level trigger.A row-level trigger fires once for each row inserted, updated or deleted. Besides the row-level triggers, we havestatement-leveltriggers. A statement-trigger fires once regardless of the number of rows affected by the tr...
/*-- an after row level trigger */ CREATE OR REPLACE TRIGGER row_trigger AFTER INSERT ON to_table FOR EACH ROW BEGIN DBMS_OUTPUT.PUT_LINE('After Insert Row Level'); END; / -- a before statement level trigger CREATE OR REPLACE TRIGGER before_statement_trigger ...
上图显示了语句级出发器的行为。同时也显示了在Before statement触发器和After statement触发器间的行级触发器的触发情况。如果一个update SQL语句更新三行,那么行级触发器触发三次,语句级触发器触发一次。 二、insert 语句级触发器定义语法 语法如下: CREATE OR REPLACE TRIGGER trigger_name ...
Oracle Form中的Trigger有三个层级:Form level、Data Block level、Item level。 三个层级的影响范围是依次递减的,三个层级可能存在相同名字的Trigger,如果下层Trigger的没有定义就会使用上层的Trigger。Trigger有个继承的property可以设置,可以设置是否以及何时执行上层trigger的代码。
当n%* INDEX SCAN COST<FULL SCAN COST时,oracle会选择使用索引。在具体设置的时候,我们可以根据具体的语句来调整该值。如果我们希望某个statement使用索引,而实际它确走全表扫描,可以对比这两种情况的执行计划不同的COST,从而设置一个更合适的值。 2)db file sequential read文件顺序读取整代码,特别是表连接:该...
Enable database-level supplemental logging Enable table-level supplemental logging Execute the following statement to check whether database-level supplemental logging is enabled: SELECTsupplemental_log_data_min, supplemental_log_data_pk,supplemental_log_data_uiFROMv$database; ...