Update statement

You can use operators @, @?, @*, @+ to specify cardinality, like for the at-operator. A run-time error occurs if the number of updated records doesn't match the cardinality.

update user @ { .name == 'Bob' } ( company = 'Microsoft' );             // exactly one
update user @? { .name == 'Bob' } ( deleted = true );                   // zero or one
update user @* { .company.name == 'Bad Company' } ( salary -= 1000 );   // any number

Can change only mutable attributes.

You can match entity attributes implicitly by name or type:

val company = 'Microsoft';
update user @ { .name == 'Bob' } ( company );

Using multiple entities with aliases. The first entity is the one that's updated. You can use other entities in the where-part:

update (u: user, c: company) @ { u.xyz == c.xyz, u.name == 'Bob', c.name == 'Google' } ( city = 'Seattle' );

Can specify an arbitrary expression returning a entity, a nullable entity, or a collection of entities:

val u = user @? { .name == 'Bob' };
update u ( salary += 5000 );

You can modify a single attribute by a regular assignment syntax:

val u = user @ { .name == 'Bob' };
u.salary += 5000;