{{ item.unitName[0] }} ==null就显示空

这是一个条件语句，可以用在程序中控制数据的显示。如果`item.unitName[0]`的值为`null`，则显示空，否则会显示`item.unitName[0]`的值。可以使用如下代码实现：

{{ item.unitName[0] == null ? '' : item.unitName[0] }}

相关问题

SELECT piats.id, piats.company.name, piats.type, piats.relatedBill, piats.relatedBill2, piats.piats, piats.item.code, piats.item.name, piats.unit.unit, piats.unit.convertFigure, piats.pallet, piats.receiver, piats.scanTime, piats.beExport, piats.exportCnt, piats.exportTime, piats.exportUserName, piats.updateInfo.creator, piats.updateInfo.createdTime, piats.updateInfo.lastOperator, piats.updateInfo.updateTime, piats.udiDi, piats.udiPi FROM com.vtradex.wms.server.model.piats.WmsPiats piats left join WmsPickTicket pick on pick.code = piats.relatedBill left join WmsASN asn on asn.code = piats.relatedBill left join piats.unit where 1=1 and (case when pick.warehouse is null then asn.warehouse else pick.warehouse end) = 1 ORDER BY piats.id DESC; 报错unexpected token: on 怎么修改

根据您提供的 SQL 语句，我发现您的 left join 子句中的表名后面没有指定 ON 条件，导致报错。您可以修改为以下代码：

SELECT piats.id, piats.company.name, piats.type, piats.relatedBill, piats.relatedBill2, piats.piats, 
piats.item.code, piats.item.name, piats.unit.unit, piats.unit.convertFigure, piats.pallet, piats.receiver, 
piats.scanTime, piats.beExport, piats.exportCnt, piats.exportTime, piats.exportUserName, 
piats.updateInfo.creator, piats.updateInfo.createdTime, piats.updateInfo.lastOperator, 
piats.updateInfo.updateTime, piats.udiDi, piats.udiPi   
FROM com.vtradex.wms.server.model.piats.WmsPiats piats 
left join WmsPickTicket pick on pick.code = piats.relatedBill 
left join WmsASN asn on asn.code = piats.relatedBill 
left join piats.unit unit on unit.id = piats.unit.id 
where 1=1 and (case when pick.warehouse is null then asn.warehouse else pick.warehouse end) = 1 
ORDER BY piats.id DESC;

在 left join 子句中，我增加了对 piats.unit 表连接的 ON 条件，并且修改了 where 子句的条件。希望可以帮助到您。

优化sql：select sbr.name, sbr.sex, sbr.id_card, IF(sbs.id_card is null,'否','是') is_basic_living, sbr.nation, sbr.birth_date, sbr.phone, sbr.educational_status, sbr.is_old, sbr.is_basic_living, sbr.area_id, sbr.house_id, sbr.community_id, sbr.unit_id, sbr.building_id, sbc.community_name as communityName, sba.area_name as areaName, sbb.building_name as buildingName, sbu.unit_name as unitName, sbh.`name` as houseNo, (SELECT ITEM_VALUE FROM pub_dict_item WHERE DICT_CODE = "SC_NATION" and ITEM_CODE = sbr.nation) as nation, (@i := @i+1) AS seqNo from sc_basics_resident sbr left join sc_basics_houses sbh on sbr.house_id = sbh.house_id left join sc_basics_unit sbu on sbr.unit_id = sbu.unit_id left join sc_basics_building sbb on sbr.building_id = sbb.building_id left join sc_basics_area sba on sbr.area_id = sba.area_id left join sc_basics_community sbc on sbr.community_id = sbc.community_id left join sc_basics_special sbs on sbs.id_card = sbr.id_card ,(SELECT @i:=0) AS iTable;

你可以对这个SQL查询进行一些优化。首先，你可以尝试使用索引来加快查询速度。确保sc_basics_resident表中的house_id、unit_id、building_id、area_id和community_id列以及sc_basics_houses、sc_basics_unit、sc_basics_building、sc_basics_area和sc_basics_community表中对应的列上都有索引。

另外，你可以考虑将子查询(SELECT ITEM_VALUE FROM pub_dict_item WHERE DICT_CODE = "SC_NATION" and ITEM_CODE = sbr.nation)改为一个JOIN操作，将字典表pub_dict_item与sc_basics_resident表关联起来，以减少子查询的数量。

最后，你可以通过适当地分批查询数据，避免一次性查询过多的数据量，从而提高查询效率。