WITH I AS (
SELECT ITEM_CODE
      ,COUNT(*) AS IC
  FROM PURCHASE_HISTORY
 GROUP BY ITEM_CODE
)
, C AS (
SELECT COUNT(*) AS AC
  FROM PURCHASE_HISTORY
 GROUP BY MEMBER_CODE
)
SELECT I1.ITEM_CODE AS ITEM_A
      ,I2.ITEM_CODE AS ITEM_B
      ,ROUND((I1.IC + I2.IC) * 1.0 / (SELECT AC FROM C) * 100, 6) AS SUPPORT
      ,ROUND((I1.IC + I2.IC) * 1.0 / I1.IC * 100, 6) AS CONFIDENCE
      ,ROUND((I1.IC + I2.IC) * 1.0 / I1.IC / ((I1.IC + I2.IC) * 1.0 / I2.IC), 6) AS LIFT
 FROM I I1
     ,I I2
 WHERE I1.ITEM_CODE <> I2.ITEM_CODE
ORDER BY LIFT DESC, SUPPORT DESC , CONFIDENCE DESC, ITEM_A DESC