updateSet method
Adds a field-value pair to the UPDATE SET clause.
field The field name to update.
value The new value for the field.
Returns this to enable method chaining.
Example:
query.updateSet('name', QVar('John Doe')); // Sets name = 'John Doe' in UPDATE
Implementation
Sqler updateSet(String field, QVar value) {
_update[field] = value;
return this;
}