t_girl=# \d insert_ignore Table "ytt.insert_ignore" Column | Type | Modifiers ----------+------------------------+----------- id | integer | not null log_time | time without time zone | Indexes: "insert_ignore_pkey" PRIMARY KEY, btree (id) t_girl=# select * from insert_ignore; id | log_time ----+---------------- 1 | 14:44:12.37185 (1 row)
我來演示下幾種代替方法。
第一種方法， 用自帶的規則（RULE）來實現。
t_girl=# create rule r_insert_ignore as on insert to insert_ignore where exists (select 1 from insert_ignore where id = new.id) do instead nothing;
CREATE RULE
這時，我們插入兩條記錄，其中一條的主鍵值已經存在，直接忽略掉。 實際插入的記錄數為1.
t_girl=# insert into insert_ignore values(1,current_time),(2,current_time);
INSERT 0 1
t_girl=# select * from insert_ignore;
id | log_time
----+-----------------
1 | 14:44:12.37185
2 | 14:48:22.222848
(2 rows)
第二種方法， 建立一個返回NULL的觸發器函數。 那麼函數體如下：
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t_girl=# create or replace function sp_insert_ignore() returns trigger as
$ytt$
begin
perform 1 from insert_ignore where id = new.id;
if found then
return null;
end if;
return new;
end;
$ytt$ language 'plpgsql';
CREATE FUNCTION
對應的觸發器如下：
t_girl=# create trigger tr_ib_insert_ignore before insert on insert_ignore for each row execute procedure sp_insert_ignore();
CREATE TRIGGER
繼續插入兩條記錄。
t_girl=# insert into insert_ignore values (3,current_time),(2,current_time);
INSERT 0 1
t_girl=# select * from insert_ignore;
id | log_time
----+-----------------
1 | 14:44:12.37185
2 | 14:48:22.222848
3 | 15:05:33.198847
(3 rows)
OK。目的達到了。
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<strong>t_girl=# insert into insert_ignore
with ytt_test(f1,f2) as (
values(6,current_time),(3,current_time)
)
select a.* from ytt_test as a where a.f1 not in (select id from insert_ignore as b);
INSERT 0 1
查看記錄，插入了一條ID為6的記錄，忽略了ID為3的記錄。
t_girl=# select * from insert_ignore;
id | log_time
----+-----------------
1 | 14:44:12.37185
2 | 14:48:22.222848
3 | 15:05:33.198847
6 | 15:15:52.297802
(4 rows)</strong>
<strong>第四種，用存儲過程來代替INSERT處理。</strong>
t_girl=# create or replace function sp_insert_ignore ( IN f_id int, IN f_log_time time without time zone ) returns void as $ytt$ begin insert into insert_ignore values (f_id,f_log_time); exception when unique_violation then raise notice 'Duplicated Key Error on ID:%',f_id; return; end; $ytt$ language plpgsql; 第一次調用，拋出了錯誤。 t_girl=# select sp_insert_ignore(1,'14:22:35'::time); NOTICE: Duplicated Key Error on ID:1 sp_insert_ignore ------------------ (1 row) 第二次正常插入。 t_girl=# select sp_insert_ignore(8,'14:22:35'::time); sp_insert_ignore ------------------ (1 row) t_girl=# select * from insert_ignore; id | log_time ----+----------------- 1 | 14:44:12.37185 2 | 14:48:22.222848 3 | 15:05:33.198847 6 | 15:15:52.297802 8 | 14:22:35 (5 rows) t_girl=# OK，目的也達到了。
