To ensure that the correct (valid) data is being supplied to a database, a number of tests can be run. Think of 10 different tests to accomplish this task. Then compare your ideas to Table 11-9. Did you come up with the same or different things?

Figure 11.14:

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TABLE 11-9 Validation Tests and Techniques to Enhance the Validity of Data Input Validation Test Description Test to ensure that data are of proper type (e.g., all numeric, all alphabetic, all alphanumeric) Test to see if the value combinations of two or more data fields are appropriate or make sense (e.g., Does the quantity sold make sense given the type of product?) Class or Composition Combinations Expected Values Missing Data Pictures/Templates Range Reasonableness Self-Checking Digits Size Values Test to see if data are what is expected (e.g., match with existing customer names, payment amount, etc.) Test for existence of data items in all fields of a record (e.g., Is there a quantity field on each line item of a customer order?) Test to ensure that data conform to a standard format (e.g., Are hyphens in the right places for a student ID number?) Test to ensure data are within proper range of values (e.g., Is a student's grade point average between 0 and 4.0?) Test to ensure data are reasonable for situation (e.g., pay rate for a specific type of employee) Test where an extra digit is added to a numeric field in which its value is derived using a standard formula (see Figure 11-14) Test for too few or too many characters (e.g., Is social security number exactly nine digits?) Test to make sure values come from set of standard values (e.g., two-letter state codes)