In addition to the `SUBSTRING(s FROM start [FOR length])` function, SQLite implements the following string functions differently than the SQL standard: POSITION(s2 IN s), TRIM([[LEADING|TRAILING|BOTH] [c] FROM] s), CHAR[ACTER]_LENGTH(s), OCTET_LENGTH(s). I don't know if implementing them in SQLite is easy. However, this would only slightly increase portability between different RDBMS. The problem is that Oracle and SQL Server don't implement them (with one exception): [https://github.com/iwis/SQL-notes/blob/main/Functions.txt](https://github.com/iwis/SQL-notes/blob/main/Functions.txt)