Chapter 8 - Data Validation

1. Chapter 8 - Data Validation

2. Data Validation Tests Numeric Alphabetic Reasonableness (limit or range) Consistency check Existing Code Sequence Check Completeness Check Data Check Subscript Check Defensive Programming

3. Numeric Test Ensures that a numeric field contains numeric data , $ . Blanks are not numeric

4. Reasonableness Check A limit or range check Ensures that a number is within expected limits, does not exceed an upper or lower extreme

5. Consistency check Verifies that the values in two or more fields are consistent Example: Individual’s credit rating and the amount of credit a bank is willing to extend

6. Existing Code Check Each code should be explicitly checked, just because you check one code doesn’t mean the other is right. Example of bad code If sex-in = “Male” Add 1 to Number-of-Men Else Add 1 to Number-of-Women

7. IF statement Has a large number of options One of the most difficult statements to master An IF requires a CONDITION to be evaluated TRUE or FALSE

8. Four Types of Conditions Relational Class Sign Condition-Name

9. Relational Conditon Most Common Condition Compares the quantities on both sides of the relational operator to be True or False The data types being compared must be of the same type, both numeric or both nonnumeric

11. Class Test Ensures that a field contains numeric or alphabetic data in accordance with its PIC clause Numeric fields = 0 to 9 and a sign (+, -) Alphabetic = A to Z and/or blanks Alphanumeric = letters, numbers, special characters

13. Sign Test Determines whether a numeric field is positive, negative, or zero. You could use a relational test to check for the sign of a number

15. Condition-Name Test A special way of writing a relational condition that makes it easier to read 88-level entry in Data Division simplifies coding in Procedure Division

17. Compound Test Using two or more tests at a time with the AND or OR operators AND implies all conditions must be TRUE OR implies one condition must be TRUE

19. Hierarchy of Operations Which takes precedence in a nested IF? Arithmetic expressions Relational operators NOT condition AND (from left to right) OR (from left to right)

20. Implied Conditions The simple conditions with a compound condition often have the same subject as the statement If salary > 30000 and salary < 40000 If salary > 30000 and < 40000 If department = “MIS” or “ACC”

21. Nested IFs Results when either statement 1 or statement 2 is itself another IF statement, two or more Ifs in one sentence

25. Accept Statement Used to obtain the day, date, and/or time of execution