Definition of MariaDB IF Statement
MariaDB provides an IF conditional statement to the user, In which we can implement a basic IF conditional statement, IF search condition shows true or false statement during the SQL query execution. If the search condition does not match with specified value then SQL statement executes the else statement and it consists of one or more statements. IF () function totally differs from the IF statement as explained above statement. Normally IF statements have three different forms such as IF – THEN statement, IF – THEN – ELSE statement, and IF-THEN – ELSEIF – ELSE statement. With the conditional statement, we can perform different operations.
Syntax:
If condition
begin
if above-mentioned condition is true then it execute following expression
true expression;
end
else
begin
if above-mentioned condition is false then it execute following expression
false expression
end;
Explanation:
In above syntax, we use IF conditional statement with condition, here IF condition is true then it execute the true expression otherwise it goes to the else part and it execute the false expression when IF condition is false and we also use begin and end keywords to identify the IF – ELSE statement as shown in above syntax.
Flow Chart
Let’s set how the IF statement is working with the help of a flow chart as follows.
Explanation:
MariaDB IF statement should return Boolean value.
After that, we can specify the select statement with an expression that we need to execute, but it should be in parentheses.
In the above flowchart, we use START and EXIT in the IF statement to determine IF statement.
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ELSE condition of IF statement is optional that is dependent on the user.
How if statement works in MariaDB?
Let’s see how the IF statement works in MariaDB as below.
In IF statements all the specified conditions with IF statements are executed sequentially that means it executed the first condition from the statement. So let’s see how we can use IF statements in three different ways as follows.
1. IF – THEN statement
In this type we only use IF – THEN statement, in which that it executed only IF part if condition is true otherwise it executed THEN part that means if condition is false.
2. IF – THEN – ELSE statement
In this type we use IF – THEN – ELSE statement, in which if condition is true then it executed if expression and if condition is false then it executed else part of IF statement.
3. IF – THEN – ELSEIF statement.
In this, we used an ELSEIF statement with different expressions and it executed the same like above types.
When a condition is found that means true then the IF-THEN-ELSE statement will execute related expressions otherwise not evaluate any expression.
If the condition is false that means ELSE part of IF-THEN-ELSE statement will be executed. This is very impotent not that the ELSEIF and ELSE both condition are optional.
Examples
Let’s see the different examples of IF statements in MariaDB as below.
set @myId = (SELECT IF ((SELECT count(2) FROM `emp` WHERE `emp_id` = 2 AND `emp_dept`='2') = 3, TRUE, FALSE));
Explanation:
In the above example, we use IF statement with select and where clause as shown in above statement. Here we set the different values for the specified column mentioned in the above statement with Boolean expression. The final output of the above query we illustrate by using the following snapshot.
DELIMITER $$
USE sample $$
DROP PROCEDURE IF EXISTS my_demo $$
CREATE PROCEDURE
my_demo ()
BEGIN
IF 1=1
THEN
SELECT 1;
END IF;
END $$
Explanation:
In the above example, we use a delimiter to create a new procedure by using an if statement. In this example we use a sample database as shown in the above statement. After that we create a new procedure by using the create procedure statement, here we create my_demo procedure after that we use IF – THEN statement as shown in above statement. The final output of the above query we illustrate by using the following snapshot.
Now let’s see how we can combine all IF statements as follows.
DELIMITER //
CREATE FUNCTION sample_demo ( count INT )
RETURNS varchar(20) DETERMINISTIC
BEGIN
DECLARE size varchar(20);
IF count < 500 THEN
SET size = 'Low';
ELSEIF count >= 500 AND count <= 4000 THEN
SET size = 'Medium';
ELSE
SET size = 'High';
END IF;
RETURN size;
END; //
DELIMITER ;
Explanation:
In above example, we create function name as sample_demo as shown in above statement in which that we set different values by using IF statement such IF count is less than 500 THEN we set size is low, similarly ELSE IF count >= 500 AND count <= 4000 THEN we set size is medium and ELSE size is high. After that, we return size then end function, and end IF statement. The final output of the above query we illustrate by using the following snapshot.
Now see a simple example of IF – ELSE statement as follows.
DELIMITER $
CREATE PROCEDURE my_pr()
BEGIN
IF 2 = 2 THEN
SELECT 'TRUE';
ELSE
SELECT 'FALSE';
END IF;
END $
DELIMITER ;
CALL my_pr;
Explanation:
In the above example, we created procedure name as demo1 as shown in above statement, in which we use IF ELSE statement, here condition is that IF we have 4 = 4 then is select the true value otherwise it returns the false values. When we execute the above statement then it simply shows the query is ok, so for result we need to execute the procedure by using the above-mentioned statement such as call my_pr. The final output of the above query we illustrate by using the following snapshot.
In above screenshot we show the result of procedure and when we run the call my_pr then result as shown in below screenshot as follows.
CALL my_pr;
Conclusion
We hope from this article you have understood the MariaDB IF statement. From this article we have learned the basic syntax of MariaDB IF statement and we also see different examples of MariaDB IF statement. From this article we learned how and when we use MariaDB IF statements.
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