2. We listed six (6) basic steps in mapping ERDs to RDBMS tables. List them and explain how each one works.
Step 1: Map Regular Entities
If there are no composite/complex attributes, mapping of entities is straightforward
Step 2: Map
Weak Entities
Since a weak entity can not exist without the referenced entity, add the appropriate foreign
key(s)
Step 3: Map Binary Relationships
Map Binary 1:1, 1:M, and M:1
relationships
Remember that in M:1 and 1:M relationships, the
foreign key goes on the side of the MANY
Step 4: Map Associative Entities (M:M)
Create the
necessary table.
The primary
key is a composite of each of the primary keys from the associated tables and
any other keys needed to construct a unique identifier
Step 5: Map
Unary Relations
If a 1:M relationship, no additional tables
required.
If a M:M relationship, the associative table
again becomes a table
Step 6: Map
Ternary (and n-ary) relationships
Any combination other than a 1:1:1 results in an associative entity