RIGHT

The RIGHT function is used to extract a specified number of characters from the right side of a given string. This function is very useful when handling text data, especially in scenarios where you need to truncate a string based on specific rules.

Syntax

RIGHT(string, length)

• string: The original string from which characters are to be extracted.
• length: The number of characters to be extracted, must be an integer greater than or equal to zero.

Function Behavior Description

• If length equals 0, the function returns an empty string.
• If length is greater than the length of string, the function returns string itself.
• If length is less than 0, the function returns NULL.
• If string is NULL, the function returns NULL.

Practical Application Case

Case 1: Extract the last two letters of the student's name

Suppose there is a table named student that contains the names (name) and genders (gender) of students, as shown below:

Now, we want to query the last two letters of each student's name, we can use the following SQL statement:

SELECT name, RIGHT(name, 2) AS suffix FROM student;

The query results are as follows:

Example 2: Extracting the file extension from a filename

Suppose we have a string containing a filename, and we need to extract the file extension (i.e., the characters after the last dot in the filename). For example, the extension of the string "report.xls" is "xls".

SELECT RIGHT('report.xls', 4) AS file_extension;

The query result is:

Case 3: Handling Incomplete Strings

Suppose we have a string containing partial text and need to extract the last few characters, but the text length may vary. For example, handling the following strings:

• "这是一个示例文本" (length is 9)
• "示例" (length is 2)

Use the RIGHT function to extract the last 3 characters:

SELECT RIGHT('这是一个示例文本', 3) AS last_three_chars;
SELECT RIGHT('示例', 3) AS last_three_chars;

The result is as follows: