DataWindow Reference
Methods for the DataWindow Control

Description

Finds the next row in a DataWindow or DataStore in which data meets a specified condition.

Applies to

Syntax

PowerBuilder

long dwcontrol.Find ( string expression, long start, long end{, DWBuffer buffer} ) 

Return value

Returns the number of the first row that meets the search criteria within the search range. Returns 0 if no rows are found and one of these negative numbers if an error occurs:

-1 -- General error

-5 -- Bad argument

If any argument's value is null, the method returns null.

Usage

When the Find expression includes quotes

If the text you want to find includes quotes, you must treat the nested quote as doubly nested, because the DataWindow parses the string twice before the Find method uses it. Therefore, you cannot simply alternate double and single quotes, as you can in most strings.

For example, to find the name O'Connor, the Find expression can be:

"O~~~'Connor" (3 tildes and single quote) or

"O~~~~~"Connor" (5 tildes and double quote)

but not:

"O'Connor" or "O~"OConnor"

When the last row satisfies the search criteria

If you use Find in a loop that searches through all rows, you may end up with an endless loop if the last row satisfies the search criteria. When the start value becomes greater than end, the search reverses direction and Find would always succeed, resulting in an endless loop.

To solve this problem, you could make the end value 1 greater than the number of rows (see the examples). Another approach, shown below, would be to test within the loop whether the current row is greater than the row count and, if so, exit. This PowerBuilder code illustrates how:

long ll_find = 1, ll_end
ll_end = dw_main.RowCount()
ll_find = dw_main.Find(searchstr, ll_find, ll_end)
DO WHILE ll_find > 0
      ... // Collect found row
      ll_find++
      // Prevent endless loop
      IF ll_find > ll_end THEN EXIT
      ll_find = dw_main.Find(searchstr, ll_find, ll_end)
LOOP

Examples

This statement searches for the first row in dw_status in which the value of the emp_salary column is greater than 100,000. The search begins in row 3 and continues until it reaches the last row in dw_status:

long ll_found
ll_found = dw_status.Find("emp_salary > 100000", &
      3, dw_status.RowCount())

To test values in more than one column, use boolean operators to join conditional expressions. The following statement searches for the employee named Smith whose salary exceeds 100,000:

long ll_found
ll_found = dw_status.Find( &
      "emp_lname = 'Smith' and emp_salary > 100000", &
      1, dw_status.RowCount())

These statements search for the first row in dw_emp that matches the value that a user entered in the SingleLineEdit called Name (note the single quotes embedded in the search expression around the name):

string ls_lname_emp
long ll_nbr, ll_foundrow
 
ll_nbr = dw_emp.RowCount()
 
// Remove leading and trailing blanks.
ls_lname_emp = Trim(sle_Name.Text)
 
ll_foundrow = dw_emp.Find( &
      "emp_lname = '" + ls_lname_emp + "'", 1, ll_nbr)

This script excerpt finds the first row that has a null value in emp_id. If no null is found, the script updates the DataWindow object. If a null is found, it displays a message:

IF dw_status.AcceptText() = 1 THEN
      IF dw_status.Find("IsNull(emp_id)", &
            1, dw_status.RowCount()) > 0 THEN
         MessageBox("Caution", "Cannot Update")
      ELSE
         dw_status.Update()
      END IF
END IF

The following script attached to a Find Next command button searches for the next row that meets the specified criteria and scrolls to that row. Each time the button is clicked, the number of the found row is stored in the instance variable il_found. The next time the user clicks Find Next, the search continues from the following row. When the search reaches the end, a message tells the user that no row was found. The next search begins again at the first row.

Note that although the search criteria are hard-coded here, a more realistic scenario would include a Find button that prompts the user for search criteria. You could store the criteria in an instance variable, which Find Next could use:

long ll_row
 
// Get the row num. for the beginning of the search
// from the instance variable, il_found
ll_row = il_found
 
// Search using predefined criteria
ll_row = dw_main.Find( &
      "item_id = 3 or item_desc = 'Nails'", &
      ll_row, dw_main.RowCount())
IF ll_row > 0 THEN
      // Row found, scroll to it and make it current
      dw_main.ScrollToRow(ll_row)
ELSE
      // No row was found
      MessageBox("Not Found", "No row found.")
END IF
 
// Save the number of the next row for the start
// of the next search. If no row was found,
// ll_row is 0, making il_found 1, so that
// the next search begins again at the beginning
il_found = ll_row + 1

This example searches all the rows in dw_main and builds a list of the names that include a lowercase a. Note that the end value of the search is one greater than the row count, avoiding an infinite loop if the name in the last row satisfies the search:

long ll_find, ll_end
string ll_list
 
// The end value is one greater than the row count
ll_end = dw_main.RowCount() + 1
ll_find = 1
 
ll_find = dw_main.Find("Pos(last_name,'a') > 0", &
      ll_find, ll_end)
DO WHILE ll_find > 0
      //collect names
      ll_list = ll_list + '~r' &
         + dw_main.GetItemString(ll_find,'last_name')
 
      // Search again
      ll_find++
      ll_find = dw_main.Find("Pos(last_name,'a') & 
         > 0", ll_find, ll_end )
LOOP

See also

FindGroupChange

FindRequired