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How to Test Insert and Update Statements before Executing Them Jun 2, 2022 by Robert Gravelle

In some cases, running a well crafted UPDATE statement in production can save the day. Other times, a botched UPDATE can cause more harm than the initial issue. You can always execute your Data Manipulation Language (DML) statements on a development or test database, but due to differences in the data, this approach makes determining the statement's effects on the production data a craps shoot at best.

So what are some options to accurately predict what the result of an INSERT, UPDATE, or DELETE statement will be on production data before running it? Well, that depends on the database vendor and product, at least in part. There are also some solutions that enjoy widespread support. We'll be taking a look at both options in this blog.

Nested Joins Explained May 26, 2022 by Robert Gravelle

Just when you thought you knew every type of join, here comes another! Perhaps you've heard of nested joins, or even nested-loop query plans, and wondered what they were. Well, wonder no more. Today's blog will settle the mystery once and for all!

Benefits of Third-party Database Management Tools May 19, 2022 by Robert Gravelle

Having completed our series on Top SQL Query Mistakes last week, it's time to take a page from the Monty Python playbook and move on to something completely different. And that something is why database developers and administrators should consider using third-party database administration tools (DBMT) to fill the gaps left by the major database manufacturers. Regardless of price, all 3rd party DBMT provide functionality that fulfills the needs of the general DBA community by either complimenting or replacing database manufacturers' tool sets. Today's blog will highlight just a few of the benefits provided by 3rd party DBMT.

Some Top SQL Query Mistakes: Part 5 - Predicate Evaluation Order May 16, 2022 by Robert Gravelle

Predicate Evaluation Order

Just before Part 3 of this series, we took a brief pause to talk about Predicates in SQL, as they factored into mistakes related to Outer Joins. In this final installment of this series on Top SQL Query Mistakes, predicates will once again enter the picture, as we examine how predicate evaluation order can cause seemingly well constructed queries to fail with errors.

Some Top SQL Query Mistakes: Part 4 - Breaking Subqueries May 11, 2022 by Robert Gravelle

Breaking Subqueries

In this series on Top SQL Query Mistakes, we've seen several examples of SQL queries that look perfectly solid on first inspection, but can lead to erroneous results and/or performance degradation. Last week, learned how the placement of predicates can adversely affect query execution - particularly in outer joins. Today's installment will focus on subqueries, and how they can break an SQL statement when changes are made to any of its underlying tables.

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