How to see if a webpage is SQL injection vulnerable

Today I am talking about how you can see if a website is vulnerable to SQL injection. So what you are going to do to test it is by seeing in the URL if it has something that says ID equals something here is an example,postID=232 what you would do is type something like this postID=--232 and if it brings up a web page saying that there is some kind of SQL error the web page should be SQL injection vulnerable. Here is my tutorial of how to hack a site using SQL injection: http://computerperformancetricks.blogspot.ca/2013/12/sql-injection-and-google-dorks.html

hope this was useful please email me for questions or ideas enjoy.