WHILE loops are used in Oracle to repeatedly execute a block of code when a specific condition is met. The syntax is: WHILE
-- a block of code to be executed repeatedly END WHILE; The components include: Condition: a Boolean expression that determines whether the loop continues. Loop body: The block of code to be executed if the condition is true.
How to use WHILE loop in Oracle
WHILE loop is a control flow statement that is used to repeatedly execute a section when certain conditions are met code block. In Oracle, the syntax of the WHILE loop is as follows:
<code>WHILE -- 要重复执行的代码块 END WHILE;</code>
Each component is explained in detail below:
Condition:
This is a Boolean expression Formula, determines whether the loop continues to execute. If the condition is true, the loop body is executed; otherwise, the loop terminates.
Loop body:
This is the block of code to be executed if the condition is true. The loop body is executed repeatedly until the condition is false.
Example:
The following example creates a WHILE loop that continuously prompts the user for input as long as the user types a non-empty string:
DECLARE input VARCHAR2(20); BEGIN -- 循环继续,直到用户输入空字符串 WHILE input IS NOT NULL LOOP -- 提示用户输入 DBMS_OUTPUT.PUT_LINE('请输入一个字符串:'); -- 从用户接收输入 input := UPPER(DBMS_INPUT.GET_LINE()); -- 如果输入为空,则退出循环 EXIT WHEN input IS NULL; -- 否则,打印输入字符串的大写形式 DBMS_OUTPUT.PUT_LINE('您输入的字符串的大写形式是:' || input); END LOOP; END; /
Note:
- The WHILE loop will continue to execute until the condition is false. Therefore, make sure that the condition will eventually become false to avoid an infinite loop.
- You can use the EXIT statement within the loop body to explicitly exit the loop.
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