What does loop mean in sql

LOOP is a control flow structure in SQL that allows statements to be executed repeatedly until a condition is false. It contains: Initialize variables or set loop body: Repeat statement Exit condition: Loop termination condition Iteration: Repeat when exit condition is false End of loop body: Exit loop when exit condition is true

LOOP in SQL

What is LOOP?

LOOP is a control flow construct in SQL that allows you to execute a set of statements repeatedly until a certain condition is false.

LOOP syntax

<code>LOOP
  -- 要执行的语句
  EXIT WHEN <condition>;
END LOOP;</code>

LOOP working principle

1. ##Initialization:LOOP When execution begins, any variables or settings that may be needed are initialized.
2. Loop body: The loop body contains the statements to be executed repeatedly.
3. Exit conditions: The EXIT WHEN statement specifies the conditions for when the loop should terminate. If the condition is true, the loop will exit.
4. Iteration: If the exit condition is false, the loop body will be executed repeatedly.
5. End: When the exit condition is true, the loop will exit and continue executing subsequent code.

Example

The following is an example of continuously prompting the user to enter a number before the user enters a number greater than 0:

<code class="sql">LOOP
  SELECT '请输入一个大于 0 的数字：';
  INPUT num;
  EXIT WHEN num > 0;
END LOOP;</code>

Other points

Other control flow structures can be nested in LOOP, such as IF and CASE.
• You can use the BREAK statement inside the loop to exit the loop immediately.
• You can use the CONTINUE statement outside a loop to skip the remainder of the loop and continue with the next iteration.
• LOOP is useful when working with repetitive tasks or iterating over a data set.

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