Consider this relational model  and  the following questions in terms of writing SQL DDL code.

 

1. Change S_MNAME in STUDENN table from mandatory to optional attribute.
2. make a constraint for enforcing the business rule that  SKILL_ID in SKILL table has minimum 3 digits.
3. Add an attribute, DOB (Date of Birth) in STUDENT  table
4. Add default value as 0 (zero) for HOURLY_RATE attribute of  CLIENT_STUDENT table.
5. If we increase the maximum size of CID attribute in CLIENT table from four to six, what other changes  we need to do, and why?
6.  

IP CID *CNAME CLIENT NUMBER (4) VARCHAR2 (30) VARCHAR2 (30) VARCHAR2 (30) CHAR (5) * STREET * CITY ZIPCODE CLIENT_PK (CID) CLIENT STUDENT NUMBER (7.2) NUMBER (4) NUMBER (6) CLIENT STUDENT_PK (CID. SID) CLIENT STUDENT_CLIENT_FK (CID) CLIENT STUDENT_STUDENT FK (SID) HOURLY_RATE PF CID PF SID P SID . S_FNAME *S_MNAME S_LNAME STUDENT_PK (SID) SKILL LEVEL PF SID PF SKILL_ID STUDENT NUMBER (8) VARCHAR2 (30) VARCHAR2 (20) VARCHAR2 (30) t STUDENT SKILL P SKILL_ID CHAR (1) NUMBER (8) NUMBER (3) STUDENT SKILL_PK (SID, SKILL_ID) STUDENT SKILL STUDENT_FK (SID) STUDENT SKILL SKILL_FK (SKILL_ID) SKILL NUMBER (3) VARCHAR2 (20) * SKILL_NAME . SKILL_PK (SKILL_ID)