mysql查找的条件为空值_mysql 查询判断空值
select A.return_car_area, case when A.return_car_area= THEN 0 ELSE 1 END from t_base_Bq_branch A
select A.return_car_area, case A.return_car_area when THEN 0 ELSE 1 END from t_base_Bq_branch A
当这个字段return_car_area为空串的时候显示 0 否则显示1 case when 字段=条件 then 赋值 else 赋值 end
select IFNULL(b.tobranchID,9999) from t_base_task b
当tobranchID为null时显示 9999 否则显示数据库值 IFNULL(字段，赋值) 当字段为空是赋值
IFNULL(
CASE c.tasktype
WHEN 0 THEN (SELECT bpl.name FROM t_base_Bq_branch bpl WHERE c.stationId = bpl.rail_id )
WHEN 1 THEN (SELECT bpl.name FROM t_base_Bq_branch bpl WHERE c.stationId = bpl.rail_id ) ELSE END ,) toPark
select A.return_car_area, case when A.return_car_area= THEN 0 ELSE 1 END from t_base_Bq_branch A select A.return_car_area, case A.return_car_area when THEN 0 ELSE 1 END from t_base_Bq_branch A 当这个字段return_car_area为空串的时候显示 0 否则显示1 case when 字段=条件 then 赋值 else 赋值 end select IFNULL(b.tobranchID,9999) from t_base_task b 当tobranchID为null时显示 9999 否则显示数据库值 IFNULL(字段，赋值) 当字段为空是赋值 IFNULL( CASE c.tasktype WHEN 0 THEN (SELECT bpl.name FROM t_base_Bq_branch bpl WHERE c.stationId = bpl.rail_id ) WHEN 1 THEN (SELECT bpl.name FROM t_base_Bq_branch bpl WHERE c.stationId = bpl.rail_id ) ELSE END ,) toPark
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