mysql命令

select * from dxy1 ,dxy2 where dxy1.userid=dxy2.userid

select * from dxy1a left join dxy2a on dxy1a.userid=dxy2a.userid 查询2个表，所有表1，与其对应的表2的内容

上述命令查询dxy1中所有记录，并根据userid内容显示dxy2a的部分内容

mysql命令
update bmdxy set mc="河北"+mc where bm like '13%'
错误提示：
1292 - Truncated incorrect DOUBLE value: '河北'
而应用下面的命令
update bmdxy set mc=concat("河北",mc) where bm like '13%'

替换字段中的部分字符
update bmdxy set mc=replace(mc,'国外','') where bm like '9%'

update dxy47 set cityname=(select mc from bmdxy where locatedcity=bm) where cityname=locatedcity

select cityname,locatedcity from dxy47 where cityname=locatedcity

update dxy47 set doctoridentify=replace(doctoridentify,"['","")
update dxy47 set doctoridentify=replace(doctoridentify,"']","")
update dxy47 set enterprise=replace(enterprise,"[]","")

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