Don't update column if update value is null

Reducing column updates to essentials

While performing update operations, the target is often not all columns. We update the ones for which new non-null data is available and leave the rest untouched. COALESCE serves us well here too.

Here's how to implement this strategy when there are multiple columns involved:

UPDATE my_table
SET
  column1 = COALESCE(@param1, column1),    -- You shall pass... unless NULL! 
  column2 = COALESCE(@param2, column2),    -- Same goes for you buddy.
  column3 = COALESCE(@param3, column3);	 -- Not you too, NULL, not you too!
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The variables @param1, @param2, and @param3 are the potential non-null successors for column1, column2 and column3 respectively.

Juggling through complex updates

In complicated cases where the updating conditions of columns may be different, wrapping the logic in a jacket is helpful:

UPDATE my_table
SET
  column1 = CASE WHEN @param1 IS NOT NULL THEN @param1 ELSE column1 END,  -- With real powers comes non-NULL values.
  column2 = CASE WHEN @param2 IS NOT NULL AND @param2 <> column2 THEN @param2 ELSE column2 END  -- Watch out! Just NULL isn't enough for me!
WHERE @param1 IS NOT NULL OR (@param2 IS NOT NULL AND @param2 <> column2);  -- Where the magic happens... or not, if NULL.


The logic here is designed to only engage updates when necessary, conserving valuable write operations to improve performance.

Adopting Efficient Update Practices

While carrying out large-scale update operations, efficiency is king. Craft your WHERE clauses to reflect the crucial checks against your parameters and filter your impacted record set. Faster executions will be your reward.

Apply specific WHERE clauses veneering the same conditions as your updates. This aids in speedy operations and also provides a self-explanatory picture to any SQL reader.

Implementing updates strategically

A clean approach is key to retaining efficient performance, preserving data accuracy and avoiding unnecessary updates. Here's a strategic approach:

• Make sure to identify rows with unique identifiers to prevent updating the whole universe.
• Embrace multiple, succinct update statements rather than an all-encompassing one.

Advanced NULL management

What to do when dealing with sophisticated data structures or complex logics entangling with NULLs? Here are some pro-tips:

• Check NOT NULL constraints: Before you dive in, make sure that columns with NOT NULL constraint are either accompanied by a check or default value setting.
• Use transactional updates: Wrapping updates into transactions ensures to save you from any potential update disaster.
• Test your edge cases extensively: An extensive test drive with all extremes will likely prevent you from ending up in dark null-construction zones.

Deciphering NULL

In SQL, NULL are like quicksand, humble yet complex. They stand for any unknown or irrelevant value. To make you NULL-ready, keep these in mind:

• NULL is an existential crisis in itself; it's neither equals NOR not-equals to NULL. Use IS NULL OR IS NOT NULL.
• Say NO to useless overuse of COALESCE. They may come off as handy but can end up nestling bugs or inefficiencies.