While loop in MySQL
Loops are the most fundamental part of full stack development. Loops are very useful when we need to perform similar tasks again and again under certain conditions.
In this article, we will see how to use while loop in MySQL, and we will also see a relevant example along with proper explanation to make the topic easier to understand.
Using while loops in MySQL
General syntax for a while loop.
WHILE condition
DO
...
END WHILE
In this example, we will learn how to use while loop in MySQL. Take a look at the following sample query.
example:
CREATE PROCEDURE MyLoop()
BEGIN
DECLARE x INT default 1;
DECLARE str Varchar(30) default '';
WHILE x < 10 DO
SET str = CONCAT(str,x,' ,');
SET x = x+1;
END While;
SELECT str;
END
In the above example, we have created a procedure called MyLoop() in MySQL. Inside the function, we first declare a variable called x and assign its default value to 1 with the line DECLARE x INT default 1;
Furthermore, varchar()we declare a variable str of type and DECLARE str Varchar(30) default '';assign a default value to it using the line . After that, we create a while loop where we concatenate the value of x to str and increment the value of x.
SELECT str;After printing the value of str
using line.
Now we will call our procedure with the following command:
CALL MyLoop();
It provides you the following output.
Output:
1 ,2 ,3 ,4 ,5 ,6 ,7 ,8 ,9
请注意,The queries we use in this article are written in MySQL.
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