Syntax of for-loop in SQL Server

Looping variations and augmentations

Navigating through rows using OFFSET and FETCH

If you're boxing in a corner needing to rotate through rows, resembling manoeuvring a result set in sequence:

DECLARE @i INT = 0, @count INT;
SELECT @count = COUNT(*) FROM YourTable;

WHILE @i < @count
BEGIN
    -- Executing maneuvers for each row, one at a time!
    SELECT TOP 1 * FROM YourTable
    ORDER BY YourColumn
    OFFSET @i ROWS FETCH NEXT 1 ROWS ONLY;

    -- Stepping to the next row, don't want to miss anyone!
    SET @i = @i + 1;
END
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This method exploits OFFSET FETCH with an arranged query to traverse through individual rows like a stealth ninja.

Simulating DO..WHILE and REPEAT..UNTIL patterns

T-SQL lacks DO..WHILE loops in its repertoire, but hey, GOTO to the rescue:

DECLARE @continueFlag BIT = 1;
WHILE_BEGIN_LABEL: -- Our bookmark to jump back to
IF @continueFlag = 1
BEGIN
    -- Loop code, where the magic happens...
    -- The mystical condition for the loop to continue
    IF some_condition
        SET @continueFlag = 1
    ELSE
        SET @continueFlag = 0
    GOTO WHILE_BEGIN_LABEL; -- looping again because we can!
END
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In this case, the loop bravely proceeds as far as the condition allows. Flip the REPEAT..UNTIL script by reversing the exit scenario.

Ensuring loop efficacy and troubleshooting

Loop governance through flags

In circumstances where you need to pause the loop based on real-time conditions, employ a control flag, like the knight in shining armor @intFlag, to regulate loop closure:

DECLARE @intFlag BIT = 1;
WHILE @intFlag = 1
BEGIN
    -- Guess what, more loop code
    IF @someCondition
    BEGIN
        -- Alter control flag to halt loop. We have power!
        SET @intFlag = 0;
    END
    -- Continuing operations, because why not!
END
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This blueprint offers dynamic loop command grounded on inner loop phenomena.

Dodging regular pitfalls

Be aware of frequent issues encountered in loop assemblage:

• Infinite loops: Spawned by not aptly augmenting the loop counter or lacking a valid exit clause. Make sure you always exit gracefully!
• Performance slowdowns: Nested loops or ineffective queries playing the villain, slowing down execution; always think about using set-based procedures as alternative superheroes.
• Transaction log coyote moments: Huge transactions within a loop can cause the log to skyrocket, much like Wile E. Coyote!