Setting two scalar variables in one SELECT statement?

Performance perks: Why consolidate?

One SELECT statement for setting two variables is not just about writing less code, it's about boosting performance. Here's how:

1. Reduced traffic - Fewer trips to the server, because we run SQL like a green planet!
2. Shrinks parsing time - SQL Server can slide through less code.
3. Cleaner code - Easier to read, easier to maintain, easier to admire.
4. Transaction optimization - More queries = more log entries. So fewer statements keep your logs clear!

The do's and don'ts of syntax

SET @a, @b = (SELECT Column1, Column2 FROM Table);
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If you tried the above, you might have been met with SQL Server's dreaded red squiggle. Here's the right way to pacify the SQL beast:

SELECT @a = Column1, @b = Column2 FROM Table;
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That's right! SQL Server likes its variables initialized and assigned in the same statement. Happy server, happy coder.

Data extraction: The SELECT-way

Like a skilled gold miner, you need to extract values from a SELECT into your waiting variables. Here's your shovel:

• Type-Match: Make sure your bucket (variable) and gold nugget (column data) are of the same type.
• NULL-Handling: A NULL value can be a sneaky villain, overwriting your existing riches. Beware!
• The Ghost rows: When your SELECT can't find any matching rows, relax. Your variables retain their values like loyal dogs.

Handling the crowd: Multiple row scenario

When the SELECT statement returns multiple rows, your SQL Server will pick up the last returned values. It's a bit like leaving a party with the last person still hanging around.

-- It's always the last one (row) that stays
-- Guess who's coming home with me tonight (getting assigned to the variable)?
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Avoid unexpected assignations! Add an appropriate WHERE clause or be careful when applying aggregation functions.

Cost-effective initialization: Best practices

Here's how to initialize your variables effectively and keep your code neat:

• Individualism - Let each variable have its glory moment with its own declaration.
• A Safe Start - Initialization with a default value can prevent you from NULL headaches.
• Comments Commodore: Simple or complex, comments are your map through the code jungle.