Specifying selection criteria

You can enter selection criteria in the grid to specify which rows to retrieve. For example, instead of retrieving data about all employees, you might want to limit the data to employees in Sales and Marketing, or to employees in Sales who make more than $80,000.

As you specify selection criteria, PowerBuilder builds a WHERE clause for the SELECT statement.

1. Click the Criteria row below the first column for which you want to select the data to retrieve.

2. Enter an expression, or if the column has an edit style, select or enter a value.

   If the column is too narrow for the criterion, drag the grid line to enlarge the column. This enlargement does not affect the column size in a DataWindow object.

3. Enter additional expressions until you have specified the data you want to retrieve.

You can use these SQL relational operators in the retrieval criteria:

Because = is the default operator, you can enter the value 100 instead of = 100, or the value New Hampshire instead of = New Hampshire.

You can use the LIKE, NOT LIKE, IN, and NOT IN operators to compare expressions.

Use LIKE to search for strings that match a predetermined pattern. Use NOT LIKE to find strings that do not match a predetermined pattern. When you use LIKE or NOT LIKE, you can use wildcards:

• The percent sign (%), like the wildcard asterisk (*) used in many applications, matches multiple characters. For example, Good% matches all names that begin with Good.

• The underscore character (_) matches a single character. For example, Good _ _ _ matches all seven-letter names that begin with Good.

Use IN to compare and include a value that is in a set of values. Use NOT IN to compare and include values that are not in a set of values. For example, the following clause selects all employees in department 100, 200, or 500:

SELECT * from employee
WHERE dept_id IN (100, 200, 500)

Using NOT IN in this clause would exclude employees in those departments.

You can use the OR and AND logical operators to connect expressions.

PowerBuilder makes some assumptions based on how you specify selection criteria. When you specify:

• Criteria for more than one column on one line

  PowerBuilder assumes a logical AND between the criteria. A row from the database is retrieved if all criteria in the line are met.

• Two or more lines of selection criteria

  PowerBuilder assumes a logical OR. A row from the database is retrieved if the criterion in any of the lines is met.

To override these defaults, begin an expression with the AND or OR operator:

This technique is particularly handy when you want to retrieve a range of values in a column. See example 6 below.