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id (Primary key)
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token (Number of Token)
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transaction_type (Credited/Debited)
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transaction_for
(signup, buy, upgrade_plan, offer_accepted,
 applied_job, bump_offer, job_alert, profile_boost, validity expire)
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user_id (Foreign key for user)
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job_id (for the case offer_accepted, applied_job, bump_offer)
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bump_offer_id (for bump_offer)
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job_alert_id (for Job_alert)
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