Multicolumn Attribute

This smell arises when multiple serial columns are created for an attribute.

In cases when an attribute may have one or more values, it is tempting to create multiple columns for the attribute in a table. However, such a schema design makes querying the table very difficult and verbose.

Example

CREATE TABLE Bugs (
bug_id SERIAL PRIMARY KEY,
description VARCHAR(1000),
tag1 VARCHAR(20),
tag2 VARCHAR(20),
tag3 VARCHAR(20)
);

Tools

The following set of tools detects this smell: DbDeo(for SQL)

Reference

B. Karwin, “SQL Antipatterns: Avoiding the Pitfalls of Database Programming”. Pragmatic Bookshelf, 2010.