The functions that represent a single character in SQL are: SUBSTRING: Extract the substring at the specified position (provides a starting position and a length of 1) CHAR: Creates Unicode characters (accepts Unicode code points) CHR: Creates ASCII characters (Accepts ASCII code points) UNICHAR: Creates Unicode characters (Accepts character names)
Functions in SQL that represent a character
There are several functions in SQL that can help obtain or represent a single character:
1. SUBSTRING function
SUBSTRING function extracts the substring at the specified position in the string . To get a single character, provide a starting position and a length of 1.
Syntax: SUBSTRING(string, start_position, length)
Example: Get the first character in the string "Hello":
<code>SELECT SUBSTRING('Hello', 1, 1); -- 输出:H</code>
2. CHAR function
The CHAR function creates a single character from the Unicode character set. It accepts as argument an integer value that represents the code point of the Unicode character.
Syntax: CHAR(character_code)
Example: Get the Unicode character "A" (code point is 65):
<code>SELECT CHAR(65); -- 输出:A</code>
3 . CHR function
The CHR function is similar to the CHAR function, but it accepts ASCII character codes as parameters.
Syntax: CHR(character_code)
Example: Get the ASCII character "A" (code point is 65):
<code>SELECT CHR(65); -- 输出:A</code>
4 . UNICHAR function
The UNICHAR function creates a single character from the Unicode character set. It accepts a string argument that specifies the name of the character to be represented.
Syntax: UNICHAR(character_name)
Example: Get the Unicode character "asterisk" (name is "*):
<code>SELECT UNICHAR('*'); -- 输出:*</code>
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