The LENGTH() function


Informix provides the LENGTH() function to count the number of bytes of a character string expression:

SELECT LENGTH("aaa"), LENGTH(col1) FROM table 

Informix LENGTH() does not count the trailing blanks for CHAR or VARCHAR expressions, while Oracle counts the trailing blanks.

Informix LENGTH() returns 0 when the given string is empty. That means, LENGTH('')=0.

Oracle® MySQL and MariaDB

MySQL and MariaDB support the LENGTH() function, which is similar to Informix LENGTH().

The MySQL/MariaDB LENGTH() function ignores trailing blanks by default, except when sql_mode parameter defines PAD_CHAR_TO_FULL_LENGTH.

When passing NULL as parameter, the MySQL LENGTH() function returns NULL.


The SQL LENGTH() function name can be used with MySQL/MariaDB.

Note that the trailing blanks of CHAR values are counted, if the sql_mode parameter defines PAD_CHAR_TO_FULL_LENGTH. This affects CHAR columns, not string literals, considered as VARCHAR where trailing blanks are counted.