storing the numbers after the decimal point into a variable in MySQL

Question

lets say i want to store the number after the point which is (76) into a variable now. How am i supposed to do that? I will give a scenario below.

declare x (3,2);
set x = 323.76;
declare y int;
select cast(substring_index(x, '.', -1) as unsigned) into y;

Any help would be appreciated.

Answer 1

As Procedure or a finction and trigger, you can use your code(with a little change)

DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `mantisse`()
BEGIN
declare x DECIMAL(8,2);

declare y int;
set x = 323.76;
select cast(substring_index(x, '.', -1) as unsigned) into y;
INSERT INTO mytable VALUE (y);
END$$
DELIMITER ;

Or if you want to use it in a query you can use user defined variables

set @x = 323.96;
select cast(substring_index(@x, '.', -1) as unsigned) into @y;
INSERT INTO mytable VALUE (@y);

you have alreadya string so use SUBSTRING to get the 9

set @x = 323.96;
select cast(SUBSTRING(substring_index(@x, '.', -1),1,1) as unsigned) into @y;
SELECT @y;
INSERT INTO mytable VALUE (@y);

That works in the Proecdure too of course

Answer 2

You can easily get decimals from a number using MOD function:

SET @num = 323.76;
SET @decimals = MOD(@num, 1) * 100;
SELECT @decimals; -- 76.00

Dividing by 1, you can get the remainder with MOD function, which is 0.76 , and then you only need to multiply it by 100.

Answer 3

If I'm understanding the specification, it seems rather bizarre. I'd use the substring_index function to trim off everything before and including the dot. But I would do the math to arrive at a value v , 0 <= v < 1

Following the MySQL stored program pseudo-code given in the question, something like this:

DECLARE x DECIMAL(5,2);
DECLARE y BIGINT;

SET x := 323.76;
SET y := SUBSTRING_INDEX( ABS(x)-FLOOR(ABS(x)) ,'.',-1) + 0;

There might be a simpler way to do it, but this is an approach that satisfies my understanding of the specification.

As a demonstration of the expression that derives the value of y , consider:

SELECT _x
     , SUBSTRING_INDEX( ABS(_x)-FLOOR(ABS(_x)) ,'.',-1) + 0 AS _y
  FROM ( SELECT 0 AS _x
         UNION ALL SELECT 0.1
         UNION ALL SELECT 2.0 
         UNION ALL SELECT 3.3
         UNION ALL SELECT -4.00
         UNION ALL SELECT -5.55
         UNION ALL SELECT 623.76
         UNION ALL SELECT -723.76
       ) t

returns

_x       _y  
-------  -----
   0.00      0
   0.10     10
   2.00      0
   3.30     30
  -4.00      0
  -5.55     55
 623.76     76
-723.76     76