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Gouache painting: on a sunny potting bench a blue glazed flower pot sits in its blue saucer and a sage pot in its sage saucer, both pairs matched and set side by side

Composite Keys: Match Complete Pairs Instead of Separate Lists

May 23, 2007
Pinal Dave
SQL Tips and Tricks
SQL Coding Standards, SQL Joins, SQL Scripts, SQL Server

Composite keys need a complete pair match when the allowed values are defined together. I don’t split the components into independent lists. Doing so can admit combinations that were never allowed.

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SQL SERVER - 2005 Explanation Left Semi Join Showplan Operator and Other Operator

SQL SERVER – 2005 Explanation Left Semi Join Showplan Operator and Other Operator

May 23, 2007
Pinal Dave
SQL Tips and Tricks
SQL Joins

What the Left Semi Join showplan operator means, along with Left Anti Semi Join, Right Anti Semi Join and other joins you see in a text execution plan.

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A striped hand-knitted scarf on a chair, no color repeated, with two unused balls of yarn in a basket on the seat.

A Quote of the Day From a Table, With No Repeats Until All Are Used

May 23, 2007
Pinal Dave
SQL Tips and Tricks
SQL Random, SQL Scripts, SQL Server, SQL Transactions

Build a quote of the day table that rotates without repeats, handles concurrent requests, and supports a stable date-based selection.

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Person typing on a computer keyboard.

SQLAuthority News – T-Shirts in Action

May 22, 2007
Pinal Dave
SQLAuthority News
SQL T-Shirt

Here are the SQLAuthority T-shirts in action. Thank you for the great response; they ran out fast, so leave your request and I will see what I can do.

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SQL SERVER - 2005 Comparison EXCEPT operator vs. NOT IN

SQL SERVER – 2005 Comparison EXCEPT operator vs. NOT IN

May 22, 2007
Pinal Dave
SQL Tips and Tricks
SQL Index, SQL Operator, SQL Scripts, SQL Server

The EXCEPT operator returns distinct rows from the left query with no match on the right, just like NOT IN. Both give the same plan, but EXCEPT reads simpler.

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Three identical glass jars on a wooden shelf: one filled with rice, one holding a single grain, and one completely empty with its lid off.

What Is NULL in SQL Server? The Value That Isn’t a Value

May 21, 2007
Pinal Dave
SQL Tips and Tricks
Best Practices, Database, SQL Scripts, SQL Server

NULL in SQL Server is not zero and not an empty string. It means the value is unknown, and that changes every comparison you write. Why equals never matches, the NOT IN trap that returns nothing, and where NULL is allowed to live.

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A plumber pressure-tests a new copper pipe with a hand pump as a single bead of water forms at one joint.

Testing an Application for SQL Injection

May 21, 2007
Pinal Dave
SQL Tips and Tricks
Developer, Dynamic SQL, SQL Server Security, Testing

Testing an application for SQL injection on a safe copy reveals response clues and unsafe query construction before repair.

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