Detailed explanation of the return value of mysql_query() function

This article mainly introduces the detailed explanation of the return value of the mysql_query() function. Interested friends can refer to it. I hope it will be helpful to everyone.

Problem description:

I am operating mysql and when inserting data, I close the resource and PHP prompts a warning. The content is roughly as follows: you need to give mysql_free_result() a resource type.

Then, I will return the result var_dump($res) and find that it is a bool value

Analysis:

Look When reading the manual, at first glance, I feel that the mysql_query() function returns a resource type, but why is it a bool value now? Well, after reading the manual patiently, I discovered that the principle is like this, as shown in the picture below:

##Summary:From the above, we can know that when mysql_query() executes a sql statement, it does not have to release the result set whenever, but when certain operations produce a result set, it calls mysql_free_result() to release; like insert update returns bool It’s not necessary if it’s worthwhile, otherwise it will be superfluous

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