MySQL string function

The first position of a string is labeled 1

• ASCII (STR): Returns the ASCII code value of the leftmost character
• CONV (N, From_base, to_base): Converts a number between different cardinality, returns a string number of number N, or null if any argument is null. If To_base is a negative number, it is considered to be a signed count.

  Mysql> Select CONV (' a ', 2);1010mysql> Select CONV (' 6E ', 8);172mysql> Select CONV (-17, 10,-18); ' -H '

• BIN (N): Returns a binary string representation of N, equivalent to CONV (n, 10, 2).
• OCT (N)
• HEX (N)
• CHAR (N1, N2, ...): Converts the argument to an integer and returns it as a string, where the argument is equivalent to the ASCII code and returns the corresponding character.

  Mysql> Select CHAR (77, 121, 83, 81, ' 76 '); ' MySQL '

• CONCAT (str1, str2, ...): The connection string, and the numeric parameter is converted to the corresponding character.
• LENGTH (str)
• Octet_length (str)
• Character_length (str): Returns the length of a string
• LOCATE (substr, str): Returns 0 if not found, note that the subscript starts at 1
• INSTR (str, substr): Opposite to the locate () parameter
• Lpad (str, Len, PADSTR): Returns the string str, left with PADSTR fill to know len length

  Mysql> Select Lpad (' 1234 ', 5, ' AB '); A1234 '

• Rpad (str, Len, PADSTR)
• Left (str, len): Returns the leftmost Len character
• Right (str, len)
• MID (str, POS, len): Returns the string of Len at the beginning of Str from the POS position
• SUBSTRING (str, POS)
• Substring_index (str, Delim, count): Returns the left or right substring by the number of left-to-right count delimiter Delim, which returns to the left, count is negative, and the right

  Mysql> Select Substring_index (' www.mysql.com ', '. ', 2); ' Www.mysql '

• LTRIM (str): Returns a string that removes the preceding space
• RTRIM (str)
• TRIM ([Leading | TRAILING | BOTH] [remstr] from str): Delete Front | back | Both sides of the substring remstr, default to BOTH, remstr default to Spaces

  Select TRIM (TRAILING ' abc ' from ' 1234abc '); ' 1234 '

• Space (N): Returns a string consisting of N spaces
• REPLACE (str, FROM_STR, TO_STR)
• REPEAT (str, count)
• REVERSE (str)
• INSERT (str, POS, Len, newstr): STR is replaced by NEWSTR with a substring of length Len starting from the POS
• ELT (n, str1, str2, STR3, ...): if n = 1, return str1, n = 2, return str2 ...
• FIELD (str, str1, str2, STR3, ...): Returns the first number of STR
• Find_in_set (str, strlist): If STR is in Strlist, a number is returned indicating that STR appears in the first few

  Mysql> Select Find_in_set (' B ', ' a,b,c,d '); 2

• Make_set (Bits, str1, str2, ...): Returned by str1 ... Some of these are grouped into strings, separated by ', ' forms, bits binary corresponding bits if 1 then select the str,str1 corresponding bit 0,str2 corresponding bit 1 ...

  Mysql> Select Make_set (1 | 2, ' hello ', ' nice ', ' world '); Hello,nice ' mysql> make_set (4 | 2, ' hello ', ' nice ', ' world '); Nice,world ' mysql> SELECT make_set (0, ' a ', ' B ', ' C ');

• Export_set (Bits, on, off, [separator, [number_of_bits]]): A bit similar to the bits,bits binary number 1 with on, 0 bits with off, the default separator is ', ', Bits less than number_of_bits are used to complete the back

  Mysql> Select Export_set (8 | 2 | 1, ' a ', ' B ', ', ', ' 6 '); a,a,b,a,b,b

• LOWER (str): Return lowercase
• UPPER (str)
• Load_file (file_name): reads the file and returns the contents of the file as a string content, the file must be on the server, and must have access rights.
• MySQL automatically transforms the numbers and strings when necessary

  Mysql> Select 1 + ' 1 ';2mysql> select CONCAT (2, ' Test '); ' 2 Test '

MySQL string function