Review Database Application Development Access Database Development ER-diagram Forms Reports Queries

ER-diagram Entity types Strong entity type Weak entity type Relationships Cardinality constraints Participation constraints Attributes atomic attributes composite attributes single-valued, multi-valued attributes derived attributes key, partial key, surrogate key, non-key attribute

employee department project dependent works for manages works on dependents of controls supervision bdate ssn name lname minit fname sex address salary birthdatenamesex relationship name numberlocation name number number of employees startdate hours N supervisor supervisee M N 1 1 N N degree location

Mapping from ER-diagrams onto relational schemas 1.Create a relation for each strong entity type 2. Create a relation for each weak entity type 3. For each binary 1:1 relationship choose an entity and include the other’s PK in it as an FK 4. For each binary 1:n relationship, choose the n-side entity and include an FK with respect to the other entity. 5. For each binary M:N relationship, create a relation for the relationship 6. For each multi-valued attribute create a new relation 7. For each n-ary relationship, create a relation for the relationship

fname, minit, lname, ssn, bdate, address, sex, salary, superssn, dno Dname, dnumber, mgrssn, mgrstartdate Dnumber, dlocation Pname, pnumber, plocation, dnum Essn, pno, hours Essn, dependentname, sex, bdate, relationship EMPLOYEE DEPARTMENT DEPT _LOCATIONS WORKS_ON PROJECT DEPENDENT

About participation constraints If a relationship is mandatory for an entity set, then if the entity set is on the “many” side of the relationship, then a specification is required to ensure a foreign key has a value, and that it cannot be null setting the ‘required’ property for the FK in MS Access, or NOT NULL constraint in the DDL. N A c d B x y 1

cd A xyc B The “required” property for attribute c is set “yes”.

Setting the required property to Yes

If the entity set is on the “one” side of a relationship, then a check constraint or database trigger can be specified to ensure compliance. N A c d B x y 1

cd A xyc B A program should be produced to check that any value appearing in c-column in table A must appear at least once in c-column in table B.

Forms different components: -bound controls -unbound controls -calculated controls -drop-down list box (combo box) -check box -option group -command buttons

Reports seven sections: - report header - page header - group header - details - group footer -page footer -report footer

Queries different kinds of queries: - select queries - action queries Make-Table query Delete query Append-Table query Update query - Crosstab query - total queries Group by Aggregate functions: Count, sum, maximum, minimum, Average - one-to-one relationship, one-to-many relationship