Category Archives: SQL Tips n Tricks

Calculate the Running Balance

By david | Published: December 23, 2009
How to calculate the running balance on a ledger using self-joins.
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Find user’s most recent post in each thread

By david | Published: November 1, 2009
One common problem that my sequence method can help to solve is how to display the most recent entry that a user has made in each thread that the user has contributed to: SELECT * FROM posts WHERE usedid = $userid AND postid IN (SELECT t1.postid, COUNT(t1.postid) AS sequence, t1.postid <= t2.postid AS flg FROM [...]
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How to Sequence each Sub-set of Records

By david | Published: October 10, 2009
How to find/display/keep/delete the first/last n posts/records/entries for each user by using a sequence.
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