What are REPEAT , LOOP and WHILE statements used for?

In MySQL, the REPEAT, LOOP, and WHILE statements are used for controlling the flow of execution by repeating a block of code under specific conditions. Each of these looping constructs serves a different purpose and is chosen based on the requirements of the task at hand.

REPEAT Statement

The REPEAT statement is used to execute a block of code repeatedly until a specified condition becomes true. It is particularly useful when the number of iterations is not known in advance but is determined by a condition evaluated at the end of each loop iteration. The syntax for the REPEAT statement includes a REPEAT keyword followed by the block of code to execute, an UNTIL keyword with a condition, and an END REPEAT clause[2][5][18].

For example, a REPEAT loop might be used to increment a value until it reaches a certain threshold:

REPEAT
    SET @value = @value + 1;
UNTIL @value > 100
END REPEAT;

This loop will continue to increment @value until it exceeds 100.

LOOP Statement

The LOOP statement provides the simplest form of iteration in MySQL, executing an indefinite loop that continues until it is explicitly terminated by a LEAVE statement. This type of loop is useful when an indefinite number of iterations are required, and the loop needs to be exited under specific conditions[8][12][16].

An example of a LOOP statement might look like this:

label1: LOOP
    IF @x > 10 THEN
        LEAVE label1;
    END IF;
    SET @x = @x + 1;
END LOOP label1;

In this example, the LOOP will continue to execute until @x is greater than 10.

WHILE Statement

The WHILE statement is used to execute a block of code repeatedly as long as a specified condition remains true. It is known as a pre-test loop because the condition is tested before each iteration, meaning the loop may not execute at all if the condition is false at the beginning[7][9][10][13].

Here’s an example of a WHILE loop:

WHILE @a < 10 DO
    SET @a = @a + 1;
END WHILE;

This...