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Diffstat (limited to 'view/employee.hxx')
| -rw-r--r-- | view/employee.hxx | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/view/employee.hxx b/view/employee.hxx index 87f0bce..4e1b745 100644 --- a/view/employee.hxx +++ b/view/employee.hxx @@ -253,6 +253,24 @@ struct employee_country_objects shared_ptr<country> nat; }; +// An example of using inner join type. Here we want to find employers +// that have any employees. If we were to use the default left join type, +// then we would have gotten all the employers, regardless of whether +// they have any employees. By using the inner join, we make sure that +// only matching employers are returned. +// +// It is also likely that there will be more than one employee for any +// particular employer which will lead to duplicate employer records +// being returned. To avoid this we use the 'distinct' result modifier. +// +// Try to change the join type or remove 'distinct' to observe the +// change in behavior. +// +#pragma db view object(employer) object(employee inner) query(distinct) +struct employer_with_employees +{ + shared_ptr<employer> e; +}; // An example of a native view that provides a complete query and is based // on an ad-hoc table. This view allows us to load the employee vacation |