Examples

Suppose that we consider the scenario where we have three data-carriers, X, Y, and Z, whose observations are as in Table 8.2.

For our first example, suppose that there is no prior selection, and the following command is issued:

BD>select : y<=9.7

This results in the selection of cases shown in column A in Table 8.2. Suppose next that the further command is issued:

BD>select : &x

This results in the selection of cases shown in column B in Table 8.2, where a case is selected only if it appears both in the prior selection and exists for the data-carrier X. Suppose finally that this further command is issued:

BD>select : -z=18

This results in the selection of cases shown in column C in Table 8.2, where the selection is as in column B except that the case corresponding to Z=18 has been deselected.

Notice that we could have concatenated this sequence of commands as

BD>select : y<=9.7, &x, -z=18

with exactly the same result.