This is personal study note
Copyright and original reference:
https://www.youtube.com/watch?v=XR6Ycdecf2Y&list=PLVsNizTWUw7HhYtI-4GGmlJ5yxNdwNI_X
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Trigger: the code which is attached onto table,
and when table runs tasks with "insert, update, delete", that code is executed
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When member unregisters (delete trigger), that member is also managed in "unregistered table" (by copying the information from original table)
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update
check the manipulated record
delete record
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create deletedMemberTBL
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create trigger
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delete record
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Backup
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To create one file, select this option
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restore backup