Dear friend,
It follows RDBMS's rule of thumb of Dr.E.Codd. You would not able to delete parent data if child data exists. If on delete cascade option enabled then when ever you delete parent data, child data automatically deleted.
the use or the purpose of DELETE_RULE value of the ALL_CONSTRAINTS table and how it influences the referential integrity on tables...during operations like insert/update on parent and child tables?
Medical Marijuana Vaporizer
aromed vaporizer
Dear friend,
It follows RDBMS's rule of thumb of Dr.E.Codd. You would not able to delete parent data if child data exists. If on delete cascade option enabled then when ever you delete parent data, child data automatically deleted.
Create the wuery you require then use the field you want to count on then use the sigma sign next to the red examination mark.
There will be a new row at the bottom with a group by in it change it to count.
the jobs done.
If you put the same field in twice one group by the next count you will se what I mean.
Have a go if you get stuck contact me.
Oracle is based on Dr E.F. codd rules. It describes the relationship between parent table and child table. There are 12 rules in that. all provides some conditions for update, delete and select query.