res = to.join(tc,to.id1 == tc.id,how ='left')。select(to.id1.alias('Employee_id'),tc.name.alias('Employee_Name'), to.dept.alias('Employee_Dept'))res.show()
+-----------+-------------+-------------+
|Employee_id|Employee_Name|Employee_Dept|
+-----------+-------------+-------------+
| 12| Prad| Physics|
| 13| null| Chem|
| 14| null| Maths|
+-----------+-------------+-------------+
我想将空值替换为NONAME。请告知选择语法
尝试这样的事情:
df.withColumn("EmployeeNameNoNull",coalesce(df.Employee_Name,lit('NONAME'))).show()