CAST to DECIMAL in MySQL

Question

I am trying to cast to Decimal in MySQL like this:

CAST((COUNT(*) * 1.5) AS DECIMAL(2))

I\'m trying to convert the number of rows in a tabl

Answer 1

MySQL casts to Decimal:

Cast bare integer to decimal:

select cast(9 as decimal(4,2));       //prints 9.00

Cast Integers 8/5 to decimal:

select cast(8/5 as decimal(11,4));    //prints 1.6000

Cast string to decimal:

select cast(".885" as decimal(11,3));   //prints 0.885

Cast two int variables into a decimal

mysql> select 5 into @myvar1;
Query OK, 1 row affected (0.00 sec)

mysql> select 8 into @myvar2;
Query OK, 1 row affected (0.00 sec)

mysql> select @myvar1/@myvar2;   //prints 0.6250

Cast decimal back to string:

select cast(1.552 as char(10));   //shows "1.552"

Answer 2

If you need a lot of decimal numbers, in this example 17, I share with you MySql code:

This is the calculate:

=(9/1147)*100

SELECT TRUNCATE(((CAST(9 AS DECIMAL(30,20))/1147)*100),17);

Answer 3

An alternative, I think for your purpose, is to use the round() function:

select round((10 * 1.5),2) // prints 15.00

You can try it here:

Answer 4

From MySQL docs: Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC:

In standard SQL, the syntax DECIMAL(M) is equivalent to DECIMAL(M,0)

So, you are converting to a number with 2 integer digits and 0 decimal digits. Try this instead:

CAST((COUNT(*) * 1.5) AS DECIMAL(12,2)) 

Answer 5

DECIMAL has two parts: Precision and Scale. So part of your query will look like this:

CAST((COUNT(*) * 1.5) AS DECIMAL(8,2))

Precision represents the number of significant digits that are stored for values.
Scale represents the number of digits that can be stored following the decimal point.