I have 4 tables one common column (Date and Qty) and another field [sic]
I want to join 4 tables with date as common column.Some times qty will be NULL for particular date. I want to display all the dates even when one of table qty is NULL
Further details provided. [sic: where? ]
Please post DDL, so that people do not have to guess what the keys, constraints, Declarative Referential Integrity, data types, etc. in your schema are. Learn how to follow ISO-11179 data element naming conventions and formatting rules. Code should be in Standard SQL as much as possible and not local dialect.
This is minimal polite behavior on SQL forums. But I will guess you need a calendar table.