18 hours ago, complete wrote
is that done on T-SQL? I think it has to be done with the Management Studio.
The youtube video instructs to use this syntax. But what is the constraint? Which table should be altered -- the main one or the index table?
This instructional video does not explain how it is to be done. It shows how to create the required three constraints but nothing beyond that. So, what else do I do?
I don't use management studio, except to run SQL
So a constraint is, errr, a constraint on what data can go into a table. A primary key is a constraint because it tells SQL to constrain the values in the column to be unique, no duplicates.
A foreign key tells SQL to constrain values in a column to only allow values which exist in another column in another table.
So you first set up a primary key on the master column, to take one of yours, age classification. Let's assume it has an AgeId and a Description field; you'd do
ALTER TABLE AgeClassificationADD CONSTRAINT PK_AgeClassificationPRIMARY KEY CLUSTERED(AgeId)
Then you need to setup the foreign key. I will assume that your primary table is called People, and it also has an AgeID field, which you want to be the link between the two.
ALTER TABLE PeopleADD CONSTRAINT FK_People_AgeClassification_AgeIdFOREIGN KEY (AgeId)REFERENCES AgeClassification (AgeId)
So the line FOREIGN KEY (AgeId) specifies the field you are going to link to another table. REFERENCES gives the other table name and then, in brackets, the field in the other table.
Does that help?