MOD(a, b) + ABS(b) * (1 - SIGN(MOD(a, b) + 0.WARNING : The following only works with innodb_file_per_table enabledįor example, suppose your datadir was /opt/mysql/data. Then, the correct expression by which you multiply ABS(b) is: However, you need something that returns only 0 and 1, not 1 and -1. The sign function SIGN() returns 1 if its argument is strictly positive, -1 if it is strictly negative, and 0 if it equals 0. You can use any positive number less than 1 instead of 0.5. Since MOD(a, b) is always an integer, the expression MOD(a, b) + 0.5 is always positive for MOD(a, b) ≥ 0 and negative for MOD(a, b) < 0. So, we can multiply ABS(b) by an expression that equals 1 for a negative MOD(a, b) and 0 for a non-negative MOD(a, b). Note that MOD(a, b) = MOD(a, b) + ABS(b) * 0 when MOD(a, b) >= 0. In Solution 2, MOD(a, b) + ABS(b) was returned for cases when MOD(a, b) = 0. Instead of a CASE WHEN, use a more complex one-line mathematical formula: There is another way to solve this problem. Of course, you still can't divide any number by 0.
#How do you do division with mysql how to
If you need a refresher on how the ABS() function works, take a look at the cookbook How to compute an absolute value in SQL. When MOD(a, b) returns a negative number, the CASE WHEN result should be MOD(a, b) + ABS(b). MOD(-5, -3) returns -2 when it should return 1. MOD(-2, 5) returns -2 when it should return 3. How do you get the correct remainder when MOD() returns a negative value? You should add the absolute value of the divisor to MOD(a, b). Otherwise, we have to correct the result returned by MOD(a, b). When MOD(a, b) is non-negative, the remainder is simply MOD(a, b). To compute the remainder of a division between any two integers (negative or non-negative), you can use the CASE WHEN construction. Unfortunately, MOD(a, b) can return a negative value when a is negative. Getting the correct remainder is problematic when the dividend a is a negative number.
Obviously, an error is shown if the divisor b is 0, because you can't divide by 0. This is how MOD(a, b) works for the non-negative dividends in the column a.
It is a number r∈ for which there exists some integer k suchĥ = 1 * 3 + 2, so the remainder of 5 and 3 equals 2.ĩ = 3 * 3 + 0, so the remainder of 9 and 3 equals 0.ĥ = (-1) * (-3) + 2, so the remainder of 5 and -3 equals 2. Non-negative integer that is smaller than the divisor b. Mathematically, a remainder of two integers is a However, when it is negative, it doesn’t follow the mathematical definition of the remainder.Ĭonceptually, a remainder is what remains after an integer division of aīy b. This solution works correctly if a is non-negative. Each remainder should be a non-negative integer value smaller than b. You want to compute the remainders from dividing a by b. In the table numbers, you have two columns of integers: a and b. You want to find the (non-negative) remainder.
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