Detailed explanation of character functions in MySQL database
The functions in the MySQL database can be divided into character functions, numeric operators and functions, comparison operators and functions, date and time functions, information functions, aggregate functions, encryption functions and custom functions according to their functions.
1.CONCAT()
CONCAT() function is used for character connection, as shown in the figure below:
2. The CONCAT() function can also be used to character-concatenate all records of two fields in a data table, as shown in the following figure:
3.CONCAT_WS()
The CONCAT_WS() function uses the specified delimiter to perform character concatenation. The first part of the function The first parameter is the specified separator, as shown in the following figure:
4.FORMAT()
FORMAT() function is mainly used For number formatting, a character number is finally returned. The first parameter is the number to be formatted, and the second parameter is the number of decimal places to be retained, as shown in the following figure:
5.LOWER( )
LOWER() function converts characters to uppercase letters.
6.UPPER()
The UPPER() function converts characters into lowercase letters, as shown below:
7.LEFT()
The LEFT() function is used to get the left character.
8.RIGHT()
The RIGHT() function is used to get the characters on the right, as shown in the figure below:
9.LENGTH()
The LENGTH() function is used to obtain the string length, as shown in the following figure:
10.LTRIM()
The LTRIM() function is used to remove leading spaces.
11.RTRIM()
The RTRIM() function is used to remove subsequent spaces.
12.TRIM()
TRIM() function is used to remove leading and following spaces, as shown in the following figure:
13.REPLACE()
The REPLACE() function is used for string replacement, as shown in the following figure:
14.SUBSTRING()
SUBSTRING() function is used to intercept strings. The first parameter is the starting position to intercept, and the second parameter is the number of characters to intercept.
[Note] The counting here starts from 1, not from 0, as shown in the following figure:
15. If If the second parameter is omitted, it will be intercepted to the end of the string, as shown in the following figure:
16.[NOT] LIKE
[NOT] LIKE is used for pattern matching, where % represents 0 or more characters and _ represents any 1 characters. Returns 1 for match and 0 for no match, as shown in the following figure:
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