I have to create a Table for an Assignment, I have finished it but there is still a question. I don't understand what I have to do in the ii. I just wrote a VARCHAR command but I'm not sure if this is right, because there is written range instead of maximum 2 chars like the viii.
Below is the whole exercise, hope somebody can help me.
i. Agent Agent_code -- Unique PK / Non-unique PK
ii. Agent Areacode -- Valid range / Out of range
iii.Agent Phone -- Maximum 13chars / Size too large
iv. Agent Name -- NOT NULL / NULL
v. Agent YTD_Sls -- Numeric / Wrong datatype
vi. Customer Cus_Code -- Unique PK / Non-unique PK
vii.Customer LName -- NOT NULL / NULL
viii.Customer Initial -- Maximum 2chars / Size too large
ix. Customer Renew_date -- DATE datatype / Incorrect datatype x.
For example, the first business rule requires Agent_code to be a unique PK. To confirm that this business rule has been implemented you will write an INSERT command that will attempt to insert a non-unique PK. By looking at the first row of sample data below, we could attempt to insert the non-unique value of A101, which already exists in the table. We would expect to see an error message confirming that a unique or PK was violated. This would confirm that the business rule is being enforced by the database.
You need to put a check constraint on the Areacode field, so that all entries will conform to whatever the range of valid area codes are.
Then try to insert/update a row with an invalid Areacode to make sure that it fails.