如果前一个左连接没有找到任何内容，我如何离开连接

Question

如果tbi1找到结果，它不应该加入tbi2，而是从两个表中检索结果。

这样做的想法是加入项目表，但如果没有完全匹配，则回退到加入'*'

（这与前一个问题的SQL语句相同，但是再次尝试不同。）

 SELECT 
            COALESCE(tbi1.id,tbi2.id,tbi3.id,tbi4.id,tbi5.id,tbi6.id) AS id
            ,COALESCE(tbi1.cost,tbi2.cost,tbi3.cost,tbi4.cost,tbi5.cost,tbi6.cost) AS cost
            ,COALESCE(tbi1.price,tbi2.price,tbi3.price,tbi4.price,tbi5.price,tbi6.price) AS price 
            ,COALESCE(tbi1.itemNumber,tbi2.itemNumber,tbi3.itemNumber,tbi4.itemNumber,tbi5.itemNumber,tbi6.itemNumber) AS itemNumber
            ,COUNT(COALESCE(tbi1.id,tbi2.id,tbi3.id,tbi4.id,tbi5.id,tbi6.id)) AS quantityToAdd
            ,tbl_equipment.id AS equipId    
            ,tbl_equipment.partNum
            ,tbl_equipment.nolinks
            ,tbl_addedItemCustomerPrices.customerprice AS specialPrice
            ,tbl_testTypes.isInspt
            ,tbl_testTypes.isRecharge
            ,tbl_testTypes.isRecharagable
            ,tbl_tests.nextDate AS theNextDate
        FROM 
            tbl_tests
            INNER JOIN tbl_equipment ON tbl_equipment.id = tbl_tests.equipmentId
            INNER JOIN tbl_model ON tbl_model.id = tbl_equipment.model
            INNER JOIN tbl_testTypes ON tbl_testTypes.id = tbl_tests.testTypeId 

            LEFT JOIN tbl_items AS tbi1 ON tbi1.size = tbl_model.size AND tbi1.service = tbl_testTypes.name
            LEFT JOIN tbl_items AS tbi2 ON tbi2.size = '*' AND tbi2.service = tbl_testTypes.name AND tbi1.id IS NULL 

            LEFT JOIN tbl_items AS tbi3 ON tbi3.type = tbl_model.type AND tbi3.service = tbl_testTypes.name AND tbi2.id IS NULL 
            LEFT JOIN tbl_items AS tbi4 ON tbi4.type = '*' AND tbi4.service = tbl_testTypes.name AND tbi3.id IS NULL 

            LEFT JOIN tbl_items AS tbi5 ON tbi5.category = tbl_model.category AND tbi5.service = tbl_testTypes.name AND tbi4.id IS NULL 
            LEFT JOIN tbl_items AS tbi6 ON tbi6.category = '*' AND tbi6.service = tbl_testTypes.name AND tbi5.id IS NULL 

            LEFT JOIN tbl_addedItemCustomerPrices ON COALESCE(tbi1.id,tbi2.id,tbi3.id,tbi4.id,tbi5.id,tbi6.id) = tbl_addedItemCustomerPrices.itemId AND tbl_addedItemCustomerPrices.customerid = $currentSite 
        WHERE 
            ((nextDate >= '$startDate' AND nextDate <= '$endDate' ) OR tbl_testTypes.isRecharge = 'true')
            {$monthEndQuery}
            AND tbl_equipment.site = $currentSite 
        GROUP BY COALESCE(tbi1.id,tbi2.id,tbi3.id,tbi4.id,tbi5.id,tbi6.id)
        ORDER BY tbl_equipment.id, isRecharagable DESC