Use MySQL's MOD function to find the remainder of the modular operation

Use MySQL's MOD function to find the remainder of the modular operation

In the MySQL database, the MOD function can be used to perform the modular operation, that is, to find the remainder of two numbers. This article will introduce how to use the MOD function to perform modular operations and give corresponding code examples.

The syntax of the MOD function is as follows:
MOD(N, M)

Among them, N and M are the two numbers to be performed modulo operation, N is the dividend, and M is the divisor. The MOD function returns the remainder of N divided by M.

The following is a simple example that shows how to use the MOD function to find the remainder of two numbers:

SELECT MOD(10, 3);

The result of this query will return 1, because the remainder of 10 divided by 3 is 1 .

In practical applications, we can use the MOD function to determine whether a number is even. Modify the above example code as follows:

SELECT IF(MOD(10, 2) = 0, '偶数', '奇数');

The result of this query will return "even number", because the remainder of 10 divided by 2 is 0, indicating that 10 is an even number.

In addition to integers, the MOD function can also be used to handle decimals. Here is an example that shows how to use the MOD function to find the remainder of two decimals:

SELECT MOD(5.5, 2.1);

The result of this query will return 1.3, because the remainder of 5.5 divided by 2.1 is 1.3.

In addition to common numerical types, the MOD function can also be used to process date types. Here is an example that shows how to use the MOD function to find the remainder of two dates:

SELECT MOD(DATEDIFF('2022-12-31', '2021-01-01'), 7);

The result of this query will return 2 because there is a difference from January 1, 2021 to December 31, 2022 729 days, the remainder divided by 7 is 2. This remainder can be used to express the number of weeks between two dates.

In practical applications, the MOD function can also be used in combination with other MySQL functions and statements to implement more complex logic. For example, you can use the MOD function to determine whether a date is a weekend and to calculate how many weekends there are in a certain time period. The specific sample code is as follows:

SELECT COUNT(*) FROM t WHERE WEEKDAY(date) IN (5, 6) AND MOD(DATEDIFF(CURDATE(), date), 7) < 5;

This query will return the number of records with weekend dates in table t, and only count weekends within the last five days.

Summary:

The MOD function is a commonly used function in the MySQL database. It can be used to perform modular operations and find the remainder of two numbers. Whether it is an integer or a decimal, or even a date type, the MOD function will work fine. More complex logic can be implemented by combining it with other MySQL functions and statements. Mastering the use of the MOD function will help developers perform more mathematical and logical operations in the MySQL database.

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