Can I Inner Join 2 tables based on multiple values for a column

问题

This is what I want,

TableA Inner Join TableB 
      on TableA.ColumnA = TableB.ColumnA OR TableB.ColumnA = NULL

It gives no results back, any alternative ?

Edit

回答1:

One issue in your query is TableB.ColumnA = NULL.

NULL is undefined and you cannot use comparison operators to check null.

Replace

TableB.ColumnA = NULL

With

TableB.ColumnA IS NULL

By looking at the picture description, I think you are looking for a LEFT/RIGHT JOIN.

来源：https://stackoverflow.com/questions/24733450/can-i-inner-join-2-tables-based-on-multiple-values-for-a-column