Tag Archives: where clause

Debugging sql joins and filters in Oracle

This is a basic tip that will save time when a query isn’t returning the expected results (typically, it’s bringing back an empty set) and you need to find out which join or WHERE clause filter is causing the problem. It’s not impossible to do, of course, but it’s nice to have a method that gets a result quickly without too many edits. Take the following query, which should run on your Oracle instance: Continue reading Debugging sql joins and filters in Oracle

SQL Tricks for Tricky Logic

One reason occasionally offered for using dynamic SQL widely, or even for keeping business logic out of database stored procedures, is the difficulty of coding optional filters in SQL. Sometimes we may want a row from table X where column A = this, column B = this and column C = this. Other times we may want all the rows where column A = this but we’ll accept any value in columns B and C. Continue reading SQL Tricks for Tricky Logic