4.5.3.2 Working with Data Values as Dates

If a page item contains a date value, then using its value as a VARCHAR2-typed bind variable can raise an error if the page item uses a different format mask than the application default.

For example, consider the following where clause using the value of a Date Picker page item as a bind variable:

HIREDATE < :P34_HIRED_BEFORE

If the page item uses format mask DD-MON-YYYY and the application default is DS for the short date format of the current locale, then the page encounters the error below at runtime:

ORA-01858: A non-numeric character was found instead of a numeric character.

The solution is to reference the value as a date using the GET_TIMESTAMP() function in the APEX_SESSION_STATE package like this. Notice the bind variable notation is replaced by passing the name of the page item to the GET_TIMESTAMP() function.

HIREDATE < apex_session_state.get_timestamp('P34_HIRED_BEFORE')

This automatically accounts for any format mask you might have configured on the page item to correctly convert the value to a date result. Forgetting this can also lead to unexpected results, especially when comparing date values.

Consider the following query by example page featuring a P1_HIREDATE_RANGE_START and P1_HIREDATE_RANGE_END page items of type Date Picker.

Figure 4-6 Date Range Using Two Date Picker Page Items

Description of "Figure 4-6 Date Range Using Two Date Picker Page Items"

If you define a validator Check Hiredate Range with the PL/SQL expression below, the user submitting a low value of 22-MAY-2025 and a high value of 30-APR-2025 does not receive a validation error as expected. This happens because the two string values get compared in text order rather than date order.

:P1_HIREDATE_RANGE_START <= :P1_HIREDATE_RANGE_END

To have the values compared as dates, rewrite the validation rule as follows:

apex_session_state.get_timestamp('P1_HIREDATE_RANGE_START')
 <= apex_session_state.get_timestamp('P1_HIREDATE_RANGE_END')

With this solution in place, clicking Find Employees now produces the expected validation error as shown below, "Hiredate Range ends before it starts."

Figure 4-7 Expected Validation Error Treating Date Items as Dates

Description of "Figure 4-7 Expected Validation Error Treating Date Items as Dates"

Tip:

When working with date or timestamp values of Interactive Grid columns, convert the column's VARCHAR2 value to a date using the to_date or to_timestamp function with an appropriate format mask.