Problem 1.
1. Create the E-R diagram.
2. List the primary keys, candidate keys, weak entities (if any), partial keys (if any), total participation and any key constraints
primary keys:
Candidate Keys:
Weak entities
Partial Keys
Total Participation 
Constraints
3. Turn the E-R diagram into tables (relational model schema). Provide the SQL CREATE TABLE statement for each table in the relational schema.
Problem 2
1. Give an E/R diagram for this database. List the primary keys, candidate keys, weak entities (if any), partial keys (if any), total participation and any key constraints
2. Turn the E-R diagram into tables (relational model schema). Indicate primary and candidate keys and foreign keys. Give the SQL statements to create the corresponding relations in a relational DBMS
Problem 3
Product ( maker, model, type)
PC (model, speed, ram, hd, price)
Laptop (model, speed, ram, hd, screen, price)
Printer (model, color, type, price)
1. What PC models have speed at least 3?
Sol: \(\pi_{model}\left(\sigma_{speed\ge3}\ PC\right)\)
2. Which manufacturers make laptops with hard disks at least 100GB?
Sol:  \(\pi_{ma\ker}\left(\Pr oduct\bowtie\sigma_{hd\ge100\ }\left(Laptop\right)\right)\)
3. Find the manufacturers that make Laptops but not PCs.
Sol:  pending
4. Find the hard disk sizes that occur in two or more PCs.
Sol:     \(\rho\left(P1,PC\right)\) 
            \(\rho\left(P2,PC\right)\)    
             \(\pi_{hd}\left(P1\bowtie_{\left(P1.model<>P2.model\ AND\ P1.hd=P2.hd\right)}P2\right)\)
5. Find the manufacturer(s) of the PC(s) with the highest available speed.
 Sol:       pending
Problem 4
1. Find the name and the SSN of everyone who works more than 100 hours on a project located in Boston.
Sol:
2. Find the name and SSN of everyone who works for department number 1 and also works on project number 2.
Sol:
3. Find the name and the SSN of everyone who works on at least two projects.
Sol:
4. Find the name and the SSN of everyone who works on all projects.
Sol: