INSERT ... WHERE NOT EXISTS錯誤

Question

我有語法錯誤，我的代碼

$insert = @mysql_query("INSERT INTO topics (t_title, t_desc, t_pic, t_link, t_date,cat_id) 
SELECT '$t_title','$t_desc','$t_pic','$t_link','$t_date','$cat_id' 
WHERE NOT EXISTS (SELECT t_link 
FROM topics 
WHERE t_link = $t_link 
) 
")or die(mysql_error()); 

這將返回一個錯誤：

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE NOT EXISTS (SELECT t_link FROM topics WHERE t_link = 'showthread.php?t=120' at line 3 

我認爲這個問題是t_link = $ t_link

但是，當我用正常值替換它時，問題仍然存在。

任何幫助？

Answer 1

你錯過了第一FROM選擇了FROM子句，請檢查作爲解決chumkiu的回答，不是我

SELECT '$t_title','$t_desc','$t_pic','$t_link','$t_date','$cat_id' 
# MISSED HERE FROM ??? 
WHERE NOT EXISTS 

Answer 2

這裏的解決方案。

create table a (i int); 

insert into a (i) 
select 1 
from dual 
where 1=2; 

insert into a (i) 
select 3 
from dual 
where 1=1; 

Results

Answer 3

如果t_link是在表中唯一索引，你可以這樣做：

$insert = @mysql_query("INSERT IGNORE INTO topics (t_title, t_desc, t_pic, t_link, t_date,cat_id) 
    VALUES ('$t_title','$t_desc','$t_pic','$t_link','$t_date','$cat_id'); 

的IGNORE關鍵字告訴它什麼也不做，如果插入會複製一個唯一的密鑰約束。