Mysql Prepared Statement with Constraint - mysql

Question

I have a Table Structure as below
CREATE TABLE `eatables` (
`Sno` int(11) NOT NULL auto_increment,
`Name` varchar(255) collate latin1_general_ci default NULL,
PRIMARY KEY (`Sno`)
);
The Table contains Rows as below
insert into `eatables`(`Sno`,`Name`) values (1,'Apples');
insert into `eatables`(`Sno`,`Name`) values (2,'Oranges');
insert into `eatables`(`Sno`,`Name`) values (3,'Papaya');
insert into `eatables`(`Sno`,`Name`) values (4,'Jackfruit');
insert into `eatables`(`Sno`,`Name`) values (5,'Pineapple');
insert into `eatables`(`Sno`,`Name`) values (6,'Mango');
I created a Procedure to get the Count based on Name as Constraint
DROP PROCEDURE IF EXISTS proc_fruit_count;
CREATE PROCEDURE mp_user_preference(pFruitName VARCHAR(255))
BEGIN
SELECT #lngCount = COUNT(Sno)
FROM eatables
WHERE Name = pFruitName;
SELECT #lngCount;
END
But my Procedure is returning Null every time I execute it.

Answer 1

You have to modify your stored procedure! You also need to use IN keyword:
CREATE PROCEDURE mp_user_preference(IN pFruitName VARCHAR(255))
BEGIN
SELECT #lngCount = COUNT(Sno)
FROM eatables
WHERE Name = pFruitName;
SELECT #lngCount;
END
See http://www.mysqltutorial.org/stored-procedures-parameters.aspx
Edit:If you want to return lngCount you can modify the stored procedure as follow:
CREATE PROCEDURE mp_user_preference(IN pFruitName VARCHAR(255), OUT toReturn INT)
BEGIN
SELECT #lngCount = COUNT(Sno)
FROM eatables
WHERE Name = pFruitName
INTO toReturn;
END

Answer 2

You don't need a stored procedure here. You can solve this conveniently with a prepared statement.
prepare stmt from 'select count(*) from eatables where name = ?';
set #whatever = 'Mango';
execute stmt using #whatever; /* #whatever replaces the ? in the query above */
/* and if you don't need the prepared statement any more you do... */
deallocate prepare stmt;
Read more about prepared statements here.