MYSQL - not equal joins not working properly -

I'm having trouble finding a query to work properly, I think it should be easy, but for some reason I can not find this right.

I have two tables added to the ID field. I have all the records which are in t1 and are not visible in T2.

It currently works: AID = b.template on joining a left at AT_ templates, select

However, I want to put another condition in the query to limit the data in a subsection and it is not working: A.id = b.template where b.at_id! = 1

The second query is empty, but I want the same results as before on the basis of the input of at_id.

Any thoughts?

Your work example shows that you can record from "first table" to a Want to see and "second table" which you want to use for excluded records b if you leave all the records present in b , then you can not set any value such as b.at_id result because is in your result set b There is no value associated with

Additionally, if the condition is b.at_id is empty is true, condition b.at_id! = 1 will never be true because (the reason is that null is not a value, it is a placeholder showing absence of a value.)

If you want to get similar results from both queries based on comparison between some user input parameters and fields b.at_id (and note that your second query is currently a blank Set), you may be able to use it The Khit ways:

  SELECT * FROM at_templates as a.id = b.template a lower zone at_vault AS b where b.at_id & lt; = & Gt; 1;   
 This is a MySQL extension, not standard syntax; Unfortunately, the ANSI SQL standard syntax is different from  IS [no] , not widely supported.  
 Keep in mind that if you have some values ​​of  b.at_id  in the future that are not 1, this query will return those lines as well, and from your first query Only rows were not returned   

 




  

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