Using IF ELSE statement based on Count to execute different Insert statements

Variables and temporary flags for structured decisions

Complex problems warrant structured solutions. For such problems, delegate decision-making to temporary flags (variables) in your IF ELSE constructs. Here's how to do it:

DECLARE @recordExists BIT;
SELECT @recordExists = CASE WHEN EXISTS (SELECT 1 FROM source_table WHERE condition) THEN 1 ELSE 0 END;

-- Exploiting side effects for fun and profit
IF @recordExists = 1 
BEGIN
    -- Insert based on existence check.
    INSERT INTO target_table (columns) VALUES (values for existing data);
END
ELSE
BEGIN
    -- Covering my non-EXISTence with default insert
    INSERT INTO target_table (columns) VALUES (default or alternative values);
END


Maintain cleaner, more self-explanatory, and efficient code with temporary flags.

EXISTS over COUNT for better performance

In certain scenarios, you may want to insert records based on the existence of other records. The EXISTS function comes to the rescue:

-- Does it exist, or are we in a philosophical debate?
IF EXISTS (SELECT 1 FROM source_table WHERE some_column = 'target_data') 
BEGIN
    -- Performing the insert if existential crisis is resolved positively
    INSERT INTO target_table (columns) VALUES (values);
END
ELSE 
BEGIN
    -- Life goes on, even with existential disappointment
    INSERT INTO target_table (columns) VALUES (other_values);
END


EXISTS boosts performance as it halts the moment a match is found. It's more efficient than COUNT for checking existence.

Trade-offs, testing for multi-scenarios, and coping with edge cases

In SQL, simplicity and complexity often wrestle. To determine who wins, think about your use-cases and perform rigorous testing on different data scenarios, including edge cases and unexpected inputs. Your decision can be the difference between a pat-on-your-back and dark-under-eye-circles 😉

Writing efficient conditions with clarity

Your SQL code becomes efficient when combined with clear and practical conditions. Always replace placeholders with accurate table columns and data values. Here's an example:

-- Cooking dilemma: Omelette or Tomato Rice?
IF EXISTS (SELECT * FROM ingredients WHERE type = 'egg' HAVING COUNT(*) >= 2)
BEGIN
    -- Enough eggs! Omelette is on the menu
    INSERT INTO recipes (name, ingredients) VALUES ('Omelette', 'eggs, cheese, spinach');
END
ELSE
BEGIN
    -- Egg shortage, fallback to Tomato Rice
    INSERT INTO recipes (name, ingredients) VALUES ('Tomato Rice', 'rice, tomato, cheese');
END


Such code not only ensures correct recipe selection but also guards unnecessary recipe attempts when ingredients are in dearth.

Measures for maximizing clarity and efficiency

While wrestling with complexity, never let go of readability. Having complex expressions? Break them into snippier parts with variables. Sneak in comments to explain your decisions. Follow clear and consistent naming conventions.

For ensuring efficiency in SQL, minimize costly operations like total-table scans. Choose the right tools and functions to get things done. COUNT where needed, EXISTS where applicable.