What are the data accuracy and precision control techniques for learning MySQL?

What are the data accuracy and precision control techniques for learning MySQL?

MySQL is a commonly used relational database management system used to store and manage large amounts of data. In MySQL, data accuracy and accuracy control are very important, which determines the accuracy of our data storage and operation. This article will introduce the precision and accuracy control techniques of data in MySQL, and illustrate it with code examples.

1. Data precision
   The precision of data refers to the number of significant digits of the data. In MySQL, we can use different data types to control the precision of data. The following are some commonly used data types and their precision ranges:

• INT: Integer type, the precision range is -2147483648 to 2147483647.
• FLOAT and DOUBLE: Floating point number type, the precision range is an approximation of plus or minus 3.402823466E 38.
• DECIMAL: High-precision decimal number type, the precision range is plus or minus 10^38-1, you can control the number of digits before and after the decimal point by specifying the precision and scale.

Here is some sample code that demonstrates how to create tables and fields with different precisions in MySQL:

CREATE TABLE example (
    id INT,
    price DECIMAL(10,2),
    quantity INT
);

In the above example, we created a file called example table, in which the id field is of integer type, the price field is of DECIMAL type, the precision is 10 digits and 2 decimal places are retained, and the quantity field is also of integer type.

2. Precision Control
   In addition to controlling the precision of data through data types, MySQL also provides some functions and operators for precise control and processing of data precision. The following are some commonly used precision control techniques:

• ROUND function: This function can round a number to a specified number of decimal places. The sample code is as follows:

  SELECT ROUND(3.14159, 2);

  In the above example, we rounded the value 3.14159 to 2 decimal places and the output result is 3.14.

• TRUNCATE function: This function can truncate a number to the specified number of decimal places and discard excess decimal places. The sample code is as follows:

  SELECT TRUNCATE(3.14159, 2);

  In the above example, we truncate the value 3.14159 to 2 decimal places, and the output result is 3.14.

• FORMAT function: This function can format and display values ​​according to the specified format. The sample code is as follows:

  SELECT FORMAT(123456789.12345, 2);

  In the above example, we format the value 123456789.12345 with 2 decimal places, and the output result is 123,456,789.12.

Through the above examples, we can see that MySQL provides a wealth of functions and operators to help us accurately control and process the accuracy of data.

Summary:
Learning MySQL's data accuracy and precision control skills is very important for data accuracy and accurate operations. By choosing appropriate data types and using appropriate functions and operators, we can store and process data accurately.

We hope that the MySQL data accuracy and precision control techniques introduced in this article will be helpful to readers and they can better use MySQL for data management and processing. I wish you all good luck in your studies!

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