Portable SQL/Common/DBMS Differences
From Linuxnetworks
Differences between database implementations
NULL in column definition
This table is originally from "Building Truly Portable Database Applications in PHP": NULL
| Database | Default value | Definition allowed | Notes |
|---|---|---|---|
| Firebird | NULL | no | |
| MySQL | NULL | yes | |
| Oracle | NULL | yes | Empty strings considered NULL |
| PostgreSQL | NULL | yes | |
| SQL Server | NOT NULL | yes | |
| SQLite | NULL | yes | |
| Sybase ASE | NOT NULL | yes |
The "Definition allowed" column indicates if specifying NULL in table column definitions is allowed for CREATE TABLE statements - NOT NULL is always allowed. If "yes", the following statement doesn't generate an error:
CREATE TABLE mytable ( id INTEGER NULL )
