> ## Documentation Index
> Fetch the complete documentation index at: https://docs.baenninger.me/llms.txt
> Use this file to discover all available pages before exploring further.

# NOT NULL

Standardmässig kann ein Attributwert den Wert `NULL` bekommen. Um das zu verhindern, gibt es den `NOT NULL`-Constraint.

```sql theme={null}
CREATE TABLE Persons (
    Id INTEGER NOT NULL,
    LastName VARCHAR(45) NOT NULL,
    FirstName VARCHAR(45) NOT NULL,
    Age INTEGER
);
```

```sql theme={null}
ALTER TABLE Persons
MODIFY Age INTEGER NOT NULL;
```