章触发器创建或替换学生在之前每行声明oracle pl sql实例精解chapterscripts.pdf
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CHAPTER13
TRIGGERS
CREATEORREPLACETRIGGERstudent_bi
BEFOREINSERTONstudent
FOREACHROW
DECLARE
v_student_idSTUDENT.STUDENT_ID%TYPE;
BEGIN
SELECTSTUDENT_ID_SEQ.NEXTVAL
INTOv_student_id
FROMdual;
:NEW.student_id:=v_student_id;
:NEW.cre
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