Question

I’m building a blog engine in C# Webforms and I have the following code that selects all blog posts that are current, meaning they should be displayed and a count of all comments for each blog post and it works great.

SELECT PostID, PostTitle, PostDate, PostTeaser, Count(CommentID) AS CountOfCommentID, PostCurrent 
FROM TBLBlogPost 
    INNER JOIN TBLBlogComment ON PostID = PostCommentFK 
GROUP BY PostID, PostTitle, PostDate, PostTeaser, PostCurrent
HAVING PostCurrent = 'True'

The problem is it only selects blog posts that have at least one comment.

Does anyone know how I can fix this?

Answer 1

You should use a LEFT JOIN then, instead of the INNER JOIN

SELECT PostID, PostTitle, PostDate, PostTeaser, Count(CommentID) AS CountOfCommentID, PostCurrent 
FROM TBLBlogPost 
    LEFT JOIN TBLBlogComment ON PostID = PostCommentFK 
GROUP BY PostID, PostTitle, PostDate, PostTeaser, PostCurrent
HAVING PostCurrent = 'True'

INNER JOIN means that the matching table MUST match or else it will not fill the resultset. A LEFT JOIN means that if the match is not made, it will fill everything from that table with NULL

Here is a good visual representation of the different SQL joins.