User Guide

Data Files

The two expressions are usually connected by a relational operator, such as = or >. To

choose the relation, put your cursor in the Relation cell and either type the operator

or select it

from the drop-down menu.

Dates and ti

mes in expressions need to be specified in a special manner (including the

curly braces shown in the examples):

 Date literals should be specified using the general form: {d yyyy-mm-dd}.

 Time literals should be specified using the general form: {t hh:mm:ss}.

 Date/time literals (timestamps) should be specified using the general form: {dt

yyyy-mm-dd

hh:mm:ss}

Functions.

A selection of built-in arithmetic, logical, string, date, and time SQL

functions is provided. You can select a function from the list and drag it into

the expression, or you can enter any valid SQL function. See your database

documenta

tion for valid SQL functions. A list of standard functions is available at:

http://msdn.microsoft.com/library/en-us/odbc/htm/odbcscalar_functions.asp

Use Random Sampling. Selects a random sample of cases from the data source.

For large data sources, you may want to limit the number of cases to a small,

represen

tative sample. This can significantly reduce the time that it takes to run

procedures. Native random sampling, if available for the data source, is faster than

SPSS random sampling, since SPSS random sampling must still read the entire

data sour

ce to extract a random sample.

 Approxi

mately.

Generates a random sample of approximately the specified

percentage of cases. Since this routine makes an independent pseudo-random

decision for each case, the percentage of cases selected can only approximate

the spec

ified percentage. The more cases there are in the data file, the closer the

percentage of cases selected is to the specified percentage.

 Exactly. Selects a random sample of the specified number of cases from the

specified total number of cases. If the total number of cases specified exceeds

the tot

al number of cases in the data file, the sample will contain proportionally

fewer cases than the requested number.

Prompt

for Value.

You can embed a prompt in your query to create a parameter query.

When users run the query, they will be asked to enter information specified here. You

might want to do this if you need to see different views of the same data. For example,