DROP 仅在存在时触发 (ORACLE)
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DROP trigger only if it exists (ORACLE)
提问by Pratik Soni
I want to dropa existing trigger in ORACLE.
我想删除ORACLE 中的现有触发器。
I do know the dropquery for the trigger in oracle. But wanted to know that how can I check if that trigger is already exists in Oracle DB.
我知道oracle 中drop的触发器查询。但想知道如何检查该触发器是否已存在于Oracle DB 中。
DROP query:
删除查询：
DROP TRIGGER **TRIGGER_NAME**
回答by a_horse_with_no_name
You need a PL/SQL block with dynamic SQL for this:
为此，您需要一个带有动态 SQL 的 PL/SQL 块：
-- drop the trigger if it exists
declare
l_count integer;
begin
select count(*)
into l_count
from user_triggers
where trigger_name = 'TRIGGER_NAME';
if l_count > 0 then
execute immediate 'drop trigger trigger_name';
end if;
end;
/
-- now create the trigger
create trigger trigger_name
..
begin
end;
/
Note that (unquoted) identifiers are stored in upper case in the Oracle system catalogs. So make sure you use trigger_name = 'TRIGGER_NAME', not trigger_name = 'trigger_name'in the PL/SQL check
请注意，（未加引号的）标识符以大写形式存储在 Oracle 系统目录中。所以请确保您使用trigger_name = 'TRIGGER_NAME', 而不是trigger_name = 'trigger_name'在 PL/SQL 检查中
回答by hinotf
You have two option:
你有两个选择：
1) Check if trigger exists
1) 检查触发器是否存在
SELECT *
FROM user_triggers
WHERE trigger_name = '...'
2) DROP trigger and check for EXCEPTION
2) DROP 触发器并检查 EXCEPTION
