Constraints

Typically constraints are placed on properties. Constraints prevent undesirable data from being inserted. They also stop any updates that would violate the constraint condition. An example of this is an exclusive constraint on username:

Input

Run

describe object Account as sdl;

describe object Account as sdl;

Output Objects

Press the 'Run' button to evaluate the input

Let's try creating a new user that could clash with an existing one:

Input

Run

insert Account {
  username := 'Alice'
};

insert Account {
  username := 'Alice'
};

Output Objects

Press the 'Run' button to evaluate the input

Feel free to experiment with the above command, perhaps to make an update that would violate the exclusive username of another Account.

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