# Hadoop Hive-specific SQL limitations

A few of the following key limitations in Hive prevent some regular Metadata Editor features from working as intended, and limit the structure of your SQL queries in Report Designer:

* Outer joins are not supported.
* Each column can only be used once in a `SELECT` clause.

  Duplicate columns in `SELECT` statements cause errors.
* Conditional joins can only use the = conditional unless you use a `WHERE` clause.

  Any non-equal conditional in a **FROM** statement forces the Metadata Editor to use a Cartesian join and a `WHERE` clause conditional to limit it.