Completed Requirements for all DB_xxx classes

	modified:   CourseIT_Proj/src/java/webProj/CourseIT/Funct/DB_CourseEnroll.java
	modified:   CourseIT_Proj/src/java/webProj/CourseIT/Funct/DB_CourseHistory.java
	modified:   CourseIT_Proj/src/java/webProj/CourseIT/Funct/DB_Courses.java
	modified:   CourseIT_Proj/src/java/webProj/CourseIT/Funct/DB_Internships.java