Normally you can not use dynamically generated SQL at runtime as your prompt record. You can use %EDITTABLE to specify the prompt table you want to use, but it has to be predefined. There is this little known property SqlText for Field Class, which allows you to do exactly that.
Here is the description and sample code taken from peoplebooks.
This property is valid only for fields that have a dynamic view as their prompt record. If you set SqlText to a non-null value, that text is used instead of the dynamic view's normal text used for prompting.
Suppose you wanted to have a different prompt table depending on the settings of other fields in the row. Normally you could use %EDITTABLE to dynamically specify the prompt table you want. However in this case there are too many possible combinations of values, which would require too many views. Furthermore, the values are customizable by the end-user or the application, which means even if you, the developer, wanted to, you couldn't provide all the combinations of views necessary. However you can generate the desired SQL text for the view in PeopleCode based on what the user enters.
If you use a dynamic view as the prompt table, and have the dynamic view contain a SQL object that is updated from PeopleCode, you could achieve this functionality. However, a SQL object is a shared object, so if multiple users used the same page, they overwrite each other's settings and the SQL object contains the SQL for the most recent user. Similarly if a single user had multiple rows on a page, the SQL object is valid only for the most recent row. This means if the user went to another row and did a prompt, they would get the wrong values again.
The purpose of this property is to enable you to specify the generated SQL text independently for each occurrence in each transaction. It enables you to override the text of a dynamic view being used as a prompt table on a field by field basis.
It is up to the developer to verify that the text specified for this property is valid, that is, that it selects the correct number of fields for the record definition, and so on.
This property is read-write.
Local string &SQLSTRING;
&SQLSTRING = "SELECT DISTINCT JOURNAL_ID, BUSINESS_UNIT_IU, JOURNAL_DATE, LEDGER_GROUP, SOURCE, SYSTEM_SOURCE, PROC_PART_ID, JRNL_HDR_STATUS, DESCR FROM PS_JRNL_HEADER WHERE JRNL_HDR_STATUS IN ('N','E','V')"
If All(JRNL_EDIT_REQ.BUSINESS_UNIT) Then
&SQLSTRING = &SQLSTRING | " AND BUSINESS_UNIT_IU='" | JRNL_EDIT_REQ.BUSINESS_UNIT | "'"
If All(JRNL_EDIT_REQ.LEDGER_GROUP) Then
&SQLSTRING = &SQLSTRING | " AND LEDGER_GROUP='" | JRNL_EDIT_REQ.LEDGER_GROUP | "'"
If All(JRNL_EDIT_REQ.SOURCE) Then
&SQLSTRING = &SQLSTRING | " AND SOURCE='" | JRNL_EDIT_REQ.SOURCE | "'"
If All(JRNL_EDIT_REQ.SYSTEM_SOURCE) Then
&SQLSTRING = &SQLSTRING | " AND SYSTEM_SOURCE='" | JRNL_EDIT_REQ.SYSTEM_SOURCE | "'"
If All(JRNL_EDIT_REQ.PROC_PART_ID) Then
&SQLSTRING = &SQLSTRING | " AND PROC_PART_ID='" | JRNL_EDIT_REQ.PROC_PART_ID | "'"
GetRecord().GetField(Field.JOURNAL_ID_FROM).SqlText = &SQLSTRING;
GetRecord().GetField(Field.JOURNAL_ID_TO).SqlText = &SQLSTRING;