JIYIK CN >

This article will discuss how to print messages or data to the console in MySQL.

MySQL prints to the console

When using MySQL database, we often need to print some data or messages to the console. MySQL can use the SELECT command to accomplish this task.

The MySQL SELECT statement is mainly used to retrieve data from the database. We can also use it to print something to the console.

The return values ​​or data will be displayed in a table called result set. Normally, when we print something using SELECT statement, we can see the column headers and a row.

Print Message

Let's try this with an example.

SELECT 'Hello World' AS Message;

In the above statement, the message we want to print is "Hello world" and we have published it using the SELECT method. Also, as shown below, we have added Message as a column header so that the output will be more precise.

Output:

+-------------+
| Message     |
+-------------+
| Hello World |
+-------------+

As shown above, we can see the result set table with messages.

Print a variable

We can print a variable with a value to the console using the SELECT statement. To do this, first, we should create a procedure and then declare a variable with a data type and assign a value using the SET statement.

When declaring variables, we should do it inside the BEGIN and END blocks; otherwise, some syntax errors may occur. We can then print a message using the SELECT command.

Refer to the following example.

DELIMITER //

-- Creating the procedure
CREATE procedure myProcedure()

BEGIN
-- Declaring the variable and assigning the value
declare myvar VARCHAR(20);
SET myvar = 'Hello world';

-- Printing the value to the console
SELECT concat(myvar) AS Variable;
END //
DELIMITER ;

-- Calling the procedure
CALL myProcedure()

In the above code, we assign the value of Hello world to the myvar variable. After running the code, we can get the following result.

Output:

+-------------+
| Variable    |
+-------------+
| Hello World |
+-------------+

Additionally, this method can print a concatenated message to the console. For example, if we want to print "Sam is 10 years old", and 10 is a variable, we can print it using concatenation.

Let's convert the above scenario into the following code.

DELIMITER //

-- Creating the procedure
CREATE procedure myProcedure()

BEGIN
-- Declaring the variable and assigning the value
declare myvar INT DEfAULT 0;
SET myvar = 10;

-- Printing the value to the console
SELECT concat('Sam is ',myvar,' years old') AS Variable;
END //
DELIMITER ;

-- Calling the procedure
CALL myProcedure()

In the code block above, we have declared a variable called myvar inside the procedure: myProcedure. The myvar variable is an integer because it stores age, and age is a number.

Then we set 10 as the value of myvar variable and concatenate the message with the variable in the SELECT statement. After that, the procedure is called and when we run the code, we will get the following result.

Output:

+--------------------+
| Variable           |
+--------------------+
| Sam is 10 years old|
+--------------------+

Summarize

In this article, we have seen one of the basic features that MySQL provides us: printing to the console and how to perform it within the technology. We have seen that we can use the SELECT statement to accomplish the task, and we have looked at a few use cases where we need to print messages to the console, with some examples.

There are many more use cases and different ways to do this, but the techniques discussed in this article are the most basic and simple ways to perform the task.