Mysql basic character function

# View the current character set

SHOW VARIABLES LIKE'% char%'

# one-line function

USE myemployees

# character function

SELECT LENGTH ('') # get parameter bytes SELECT CONCAT (last_name,'_',first_name) FROM employees; # string concatenation SELECT UPPER ('aaa'); # convert to uppercase SELECT LOWER (' AAA'); # convert to lowercase

The index position in # mysql starts from 1, and sbstr and substring have the same effect.

SELECT SUBSTR ('Li Moyu fell in love with Lu Zhanyuan', 7); # intercepted Lu Zhanyuan string, all SELECT SUBSTR from 7 to later ('Li Moyu fell in love with Lu Zhanyuan', 1p3); # intercepted Li Moyu, the second number indicates the length SELECT INSTR ('Yang Buxue fell in love with Yin six', 'Yin six') AS out_put # returns the starting index position where the substring first appears in the big string, but does not return 0SELECT TRIM ('Zhang Cuishan') AS out_put; # remove the space SELECT TRIM ('a 'FROM' aaaaa aaa Cui aaaaa mountain aaaaaa') AS out_put; # remove the specified character before and after the removal, and cannot remove the SELECT LPAD ('Huang chivalrous', 10-scene') AS out_put in the middle # fill from the left * until the specified length is 10, and the string exceeds the specified length. The string will be truncated to the specified length SELECT RPAD ('Master Huang', 10 Magi') AS out_put; # filled from the right * until the specified length 10SELECT REPLACE ('Zhang Wuji falls in love with Zhou Zhiruo', 'Zhou Zhiruo', 'Zhao Min') AS out_put; # replaces all Zhou Zhi in the string with Zhao Min, not a

# case: capitalize the last name, lowercase, and then concatenate

SELECT CONCAT (UPPER (last_name),'_', LOWER (first_name)) FROM employees