MariaDB LENGTHB() Function

In MariaDB, LENGTHB() is a built-in string function that returns the length of a given string in bytes.

LENGTHB() is a synonym for LENGTH() in default mode and has more explicit semantics, you should prefer it.

If you want to get the number of characters in a string, use the CHAR_LENGTH() or CHARACTER_LENGTH() function.

If you want to get the number of bits in a string, use the BIT_LENGTH() function.

MariaDB LENGTHB() Syntax

Here is the syntax of the MariaDB LENGTHB() function:

LENGTHB(str)

Parameters

str

Required. The string whose length needs to be calculated. The parameter can be of other types, such as numbers or dates, etc., and the LENGTHB() function will first convert it to a string and then calculate the length.

If you do not provide any parameters, MariaDB will report an error: ERROR 1582 (42000): Incorrect parameter count in the call to native function 'LENGTHB'.

Return value

The MariaDB LENGTHB(str) function returns the length in bytes of the specified string, which is the number of bytes.

If the argument is NULL, the LENGTHB() function will return NULL.

MariaDB LENGTHB() Examples

This statement shows various basic uses of the MariaDB LENGTHB() function:

SELECT
    LENGTHB('Hello'),
    LENGTHB(''),
    LENGTHB(20),
    LENGTHB(-20),
    LENGTHB(+20),
    LENGTHB(NOW()),
    LENGTHB(CURDATE()),
    LENGTHB('你好'),
    LENGTHB(NULL)\G

Output:

*************************** 1\. row ***************************
  LENGTHB('Hello'): 5
       LENGTHB(''): 0
       LENGTHB(20): 2
      LENGTHB(-20): 3
      LENGTHB(+20): 2
    LENGTHB(NOW()): 19
LENGTHB(CURDATE()): 10
    LENGTHB('你好'): 6
     LENGTHB(NULL): NULL

Notice:

  • The result LENGTHB(-20) is 3. This is because the corresponding string of -20 is '-20' and LENGTHB('-20') returns 3.
  • The result LENGTHB(+20) is 2. This is because +20 is equivalent to 20, the corresponding string is '20', and LENGTHB('20') returns 2.
  • LENGTHB(NOW()) is equivalent to LENGTHB('2021-04-02 21:18:57').
  • The result of LENGTHB('你好') is 6. This is because the encoding I use here is UTF-8 and a Chinese character occupies 3 bytes.

Conclusion

The MariaDB LENGTHB() function returns the length of the given string in bytes.