mysql的case when字段为空,null
name字段为null时替换为 ‘该字段为空’
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SELECT CASE WHEN name is null THEN '该字段为空' ELSE name END as name ,email_id FROM mysql_table_name |
case when 判断null(已测试)
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SELECT ( case when cdi.DEVICE_TAG is not null then cdi.DEVICE_TAG else '暂无数据' end ) as deviceTag, ( case when cdi.DEVICE_CODE is not null then cdi.DEVICE_CODE else '暂无数据' end ) as deviceCode, ( case when sc.full_name is not null then sc.full_name else '暂无数据' end ) as deviceVendor, ( case when ct.CLASS_NAME is not null then ct.CLASS_NAME else '暂无数据' end ) as deviceTypeNameB, ( case when cdi.DEVICE_PORT is not null then cdi.DEVICE_PORT else '暂无数据' end ) as devicePort, ( case when cdi.CREATE_TIME is not null then cdi.CREATE_TIME else '暂无数据' end ) as createTimeStr -- cdi.DEVICE_TAG as deviceTag, -- cdi.DEVICE_CODE as deviceCode, -- sc.full_name as deviceVendor, -- ct.CLASS_NAME as deviceTypeNameB, -- cdi.DEVICE_PORT as devicePort, -- cdi.CREATE_TIME as createTimeStr FROM con_device_info AS cdi LEFT JOIN sys_code AS sc ON sc.code_value = cdi.DEVICE_VENDOR LEFT join con_type as ct on ct.ID=cdi.DEVICE_TYPE where cdi.ID=#{id} |
重点:
case when xxx
is null 或者is not null
总结
以上为个人经验,希望能给大家一个参考,也希望大家多多支持服务器之家。
原文链接:https://blog.csdn.net/weixin_40277264/article/details/108664454