插入记录(如果不存在) [英] insert a record if not exist

问题描述

大家好，

我对mysql中的WHERE NOT EXISTS感到困惑.我在php编辑器中使用了以下语法:我想将记录从一张表(一段时间内)一张一张地插入到tmp表中，并且我想在插入之前检查网址是否存在于tmp中，或者如果不存在，我不想如果不存在，我将插入它，这是我最终得到的代码！！但是即使tmp表为空，它也不会插入....任何建议吗?
-非常感谢

$ INSERT_SQL =(插入到tmp(company_name，link)
SELECT($ comp_name，$ url)不存在(SELECT * FROM TMP WHERE link = $ url))；
$ result2 = mysql_query($ INSERT_SQL，$ con);

Hi ALL,

I am kind of confused with the WHERE NOT EXISTS in mysql. I used this syntax in php editor: I want to insert records one by one from one table (in a while) to a tmp table and I want to check before inserting if the url is exists in tmp or not if exists I dont want to insert if not exist I wnat to insert this is a code I end up with it!!!but It doesnt insert even when the tmp table is empty....any suggestion?
-Many thanks

$INSERT_SQL=(INSERT INTO tmp (company_name,link)
SELECT ($comp_name,$url) WHERE NOT EXISTS (SELECT * FROM TMP WHERE link=$url));
$result2 = mysql_query($INSERT_SQL,$con);

推荐答案

INSERT_SQL =(INSERT INTO tmp(company_name，link)
SELECT(

INSERT_SQL=(INSERT INTO tmp (company_name,link)
SELECT (

comp_name，

comp_name,

url)不存在(SELECT * FROM TMP WHERE link =

url) WHERE NOT EXISTS (SELECT * FROM TMP WHERE link=

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