What are the string functions in MySQL?

String function

1. Return the ASCII code of the first character of string s

SELECT ASCII('AB');
---- 返回A的ASCII码值：65

2. LENGTH/CHAR_LENGTH(s)/CHARACTER_LENGTH(s) returns the number of characters of string s

SELECT LENGTH('1234');
---- 返回4

3, CONCAT(s1,s2…sn) string s1, s2 and other multiple characters Strings are merged into one string

SELECT CONCAT('hel','llo');
---- 返回hello

4. FIND_IN_SET(s1,s2) returns the position of the string matching s1 in string s2

SELECT FIND_IN_SET("c", "a,b,c,d,e");
---- 返回3

5. The FORMAT(x,n) function can format the number x as "#,.##", retain x to n digits after the decimal point, and round the last digit

SELECT FORMAT(250500.5634, 2); 
---- 返回250,500.56

6, INSERT(s1,x,len,s2) string s2 replaces the string with length len starting from the x position of s1

SELECT INSERT("google.com", 1, 6, "runnob");
---- 返回runoob.com

7, LOCATE (s1,s) Get the starting position of s1 from the string s

SELECT LOCATE('st','myteststring');
---- 返回5

8, LCASE(s)/LOWER(s) turn all letters of the string s into lowercase letters

SELECT LOWER('RUNOOB');
---- 返回runoob

9. UCASE(s)/UPPER(s) turns all letters of string s into uppercase letters

SELECT UCASE('runoob');
---- 返回RUNOOB

10. TRIM(s) removes the spaces at the beginning and end of the string s

SELECT TRIM('    RUNOOB    ');
---- 返回RUNOOB

11. LTRIM(s) removes the spaces at the beginning of the string s

SELECT LTRIM('    RUNOOB    ');
---- 返回 ’RUNOOB   ‘

12. RTRIM(s) removes the spaces at the end of string s

SELECT RTRIM('    RUNOOB    ');
---- 返回 ’    RUNOOB‘

13. SUBSTR(s, start, length) intercepts the length from the start position of string s A substring of length

SELECT SUBSTR("RUNOOB", 2, 3) AS ExtractString;
---- 从字符串 RUNOOB 中的第 2 个位置截取 3个 字符，返回UNO

14. SUBSTR/SUBSTRING(s, start, length) intercepts a substring of length from the start position of string s

SELECT SUBSTR/SUBSTRING("RUNOOB", 2, 3);
---- 从字符串 RUNOOB 中的第 2 个位置截取 3个 字符，返回UNO

15. POSITION(s1 IN s) gets the starting position of s1 from the string s

SELECT POSITION('b' in 'abc');
---- 返回2

16. REPEAT(s,n) String s is repeated n times

SELECT REPEAT('runoob',3);
---- 返回runoobrunoobrunoob

17. REVERSE(s) reverses the order of string s

SELECT REVERSE('abc');
---- 返回cba

18. STRCMP(s1 ,s2) Compare strings s1 and s2, if s1 and s2 are equal, return 0, if s1>s2, return 1, if s1###

SELECT STRCMP("runoob", "runoob");
---- 返回0

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