1，form是基于单表视图建立的，没有写on-insert此类的触发器。在视图上加了个rownum列结果导致form上的列不能更新
据说此种情形下的form会判断视图上的列是否属于基表，不属于的话会导致整个块不能更新。
2，在form界面上显示行号
在post-query里使用:system.trigger_record;
SYSTEM.CURSOR_RECORD和:system.trigger_record的区别：
SYSTEM.CURSOR_RECORD represents the number of the record where the cursor is located.
This number represents the record's current physical order in the block's list of records.
The value is always a character string.
SYSTEM.TRIGGER_RECORD represents the number of the record that Form Builder is processing.
This number represents the record's current physical order in the block's list of records.
The value is always a character string.