Join Types

[tbpowers]

When creating relationships between tables, in the DataSet Designer, is there a way to specify the join type (Inner, Left Outer, etc...)?

 

[cjard]

A relationship isnt a join per se.. or you could think of it as a left join, with the parent on the left.. A parent can have no children but a child cannot lack a parent

 

[jmcilhinney]

A relation is not a join. A relation can be one-to-one or one-to-many. A join generally uses a relation, either explicit or implicit, to retrieve data from two tables. An inner join will get only those parents that have children while an outer join will get all parents regardless of whether they have children or not. You could execute two queries on the same pair of tables, one using an inner join and one using an outer join, but that doesn't mean that the relation between the tables changes.

 

[tbpowers]

We are still trying to cascade comboboxes. The tables are related, however it is not a foreign key relation. We have yet to get it to work by creating the relationships in the dataset. We are at loss on getting this to work!

 

[jmcilhinney]

Maybe you could provide a full and clear description. We can't help if we have to guess the details.

 

[tbpowers]

Cascading Comboboxes

We have three tables with lookup information for the comboboxes. These are linked using a sub id. So for instance, the sub id in the first table is linked to the category id in the second table. Respecitvely, the sub id in the second table is linked to the category id in the third table. As you can see, from our example data below, there may be the same value and label assigned to more than one category, so these are not foreign key related. We setup a "Relation Only" relationship in the dataset, but it is not working. We appreciate any help you can provide and just let us know if more information is needed to understand our issue.

CATEGORY_ID	SUB_ID	VALUE	LABEL
PCAT	COND	CONDENSER	Condenser
PCAT	CONT	CONTROLLER	Controller
PCAT	EVAP	EVAPORATOR	Evaporator
PCAT	SENS	SENSOR	Sensor

CATEGORY_ID	SUB_ID	VALUE	LABEL
COND	COMP	COMPOSITE	Composites
COND	FASN	FASTNER	Fastner
CONT	ELCO	ELECTRIC_CONTROL	Electric Control
CONT	FASN	FASTNER	Fastner
EVAP	COMP	COMPOSITE	Composites
EVAP	DTBE	DRAIN_TUBE	Drain Tube
SENS	ELCT	ELECTRIC_CONNECTOR	Electric Connector
SENS	SEFA	SENSOR_FAILURE	Sensor Failure

CATEGORY_ID	SUB_ID	VALUE	LABEL
COMP	BRKN	BROKEN	Broken
COMP	CRKD	CRACKED	Cracked
FASN	BRKN	BROKEN	Broken
FASN	MISG	MISSING	Missing
ELCO	CNCT	CONNECTOR	Connector
ELCO	CPFL	COMPONENT_FAIL	Component Fail
ELCT	CNCT	CONNECTOR	Connector
ELCT	SFTW	SOFTWARE	Software