Sql WHERE column = everything

Dynamic SQL: column = column trickery

In the world of dynamic SQL, where we conjure up our queries on-the-spot, performing a comparison of a column to itself might come in handy:

-- Not as redundant as it seems, I promise
SELECT * FROM table WHERE column = column;
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This comparison will always hold true if the column isn't NULL. This trick is useful when the actual column name is part of your SQL sorcery, increasing readability and adding to the overall spell-casting ambiance.

Shoo, NULL values, shoo!

On those special nights when you want to leave the NULL values out of your circle:

-- Because we don't associate with NULL types here, Discriminator_5000 ain't got nothing on us
SELECT * FROM table WHERE column IS NOT NULL;
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This chant ensures integrity in your selection circle by only inviting non-NULL entries.

Wild like the West: LIKE operator with wildcards

Sometimes, we need our queries to be as wild and unrestrained as an untamed stallion:

-- Am I matching anything specific? Nope. But am I matching everything? You bet I am!
SELECT * FROM table WHERE column LIKE '%';
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Here, the % is a zero-or-more character wildcard, galloping across any sequence of characters it comes across, including the empty and barren plains.

Wrangling complexity: CASE WHEN in WHERE clause

For more intricate, labyrinth-like queries, a CASE WHEN hoedown helps lead the way:

-- Because even column value deserves a chance to be a cowboy
SELECT * FROM table
WHERE (CASE 
         WHEN @condition THEN column = @value
         ELSE column = column 
       END);
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The CASE lasso allows for conditional ricochets in our SQL showdown.

Placeholder fun with 'WHERE 1=1'

Adding WHERE 1=1 serves as a trusty placeholder:

-- The universal constant. Even in SQL, we all agree on something!
SELECT * FROM table WHERE 1=1;
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This trick makes appending additional conditions smoother than a snake oil salesman's speech.

Playing peek-a-boo with dynamic parameters

In those riveting games of hide-and-seek with optional parameters:

-- See me now? No? That's okay, I'll just blend in with everyone else.
SELECT * FROM table
WHERE (@parameter IS NULL OR column = @parameter);
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This parlor trick is great when you need your specific filter to pull a disappearing act.

Everything and the kitchen sink: equity operator

The simple and plain equality (=) operator is in every SQL wrangler's toolbelt when there's no particular value hitching a ride:

-- Yes, we're aware they're the same. We're not playing matchmaker here.
SELECT * FROM table WHERE column = column;
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It's essential for those dusty sundown showdowns involving dynamic SQL.

The NULL dilemma

It's critical to understand how to tango with NULL values as they can trip even seasoned SQL vaqueros. Master IS NOT NULL operation, it's your trusty steed in the NULL wildlands.

Refined approach: Beyond SELECT *

As we graduate into SQL honchos, restraining our queries to more than SELECT * becomes necessary, especially when dealing with large herds...ehm, datasets.

-- Customization is king! And also way less memory-heavy.
SELECT id, name FROM table 
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Preferring particular columns over * ensures proper resource allocation and coherent, concise results.