COUNT() Function in MySQL - GeeksforGeeks

22 Jan, 2021
COUNT() function :
This function in MySQL is used to find the number of indexes as returned from the query selected.
Features :
This function is used to find the number of indexes as returned from the query selected.
This function comes under Numeric Functions.
This function accepts only one parameter namely expression.
This function ignore NULL values and doesn’t count them.
Syntax :
COUNT(expression)
Parameter :
This method accepts only one parameter as given below:
expression: Specified expression which can either be a field or a string type value.
Returns :
It returns the number of indexes as returned from the query selected.
Example-1 :
Using COUNT() function and getting the output.
CREATE TABLE product
(  
user_id int NOT NULL AUTO_INCREMENT,  
product_1 VARCHAR(10),
product_2 VARCHAR(10),
price int , 
PRIMARY KEY(user_id)  
);
INSERT product(product_1, price)  
VALUES ('rice', 400);

INSERT product(product_2, price)  
VALUES ('grains', 600);

SELECT COUNT(user_id) FROM product;
Output :
2
Example-2 :
Using COUNT() function and counting float values.
CREATE TABLE floats
(  
user_id int NOT NULL AUTO_INCREMENT,  
float_val float,
PRIMARY KEY(user_id)  
);
INSERT floats(float_val)  
VALUES (3.5);

INSERT floats(float_val)  
VALUES (2.1);

INSERT floats(float_val)  
VALUES (6.3);

INSERT floats(float_val)  
VALUES (9.9);

INSERT floats(float_val)  
VALUES (7.0);

SELECT COUNT(float_val) FROM floats;
Output :
5
Example-3 :
Using COUNT() function and getting the output where MRP is greater than the number of counts of MRP.
CREATE TABLE package
(  
user_id int NOT NULL AUTO_INCREMENT,  
item VARCHAR(10),
mrp int,
PRIMARY KEY(user_id)    
);
INSERT package(item, mrp)  
VALUES ('book1', 3);

INSERT package(item, mrp)  
VALUES ('book2', 350);

INSERT package(item, mrp)  
VALUES ('book3', 400);

SELECT * FROM package
WHERE mrp > (SELECT COUNT(mrp) FROM package);
Output :
 user_id  | item     | mrp
--------------------------------
  2       | book2    | 350
--------------------------------
  3       | book3    | 400
Example-4 :
Using COUNT() function and getting the records of (MRP-sales price).
CREATE TABLE package01
(  
user_id int NOT NULL AUTO_INCREMENT,  
item VARCHAR(10),
mrp int,
sp int,
PRIMARY KEY(user_id)    
);
INSERT package01(item, mrp, sp)  
VALUES ('book1', 250, 240);

INSERT package01(item, mrp, sp)  
VALUES ('book2', 350, 320);

INSERT package01(item, mrp)  
VALUES ('book3', 400);

SELECT COUNT(mrp-sp) FROM package01;
Output :
2
Application :
This function is used to find the number of indexes as returned from the query selected.
DBMS-SQL
mysql
SQL
SQL
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