title: Why are BOOLEAN type columns problematic in relational database design?
body: <p>I've been working mostly with Oracle for the past few years, and am quite used to seeing single character varchar columns used as boolean values. </p>
  
  <p>I can also see (per stack overflow answers), that suggested type for MySQL is TINYINT. </p>
  
  <p>Now I've taken on my little side project - using DerbyDB, and it supports BOOLEAN columns, but not until after version 10 or so.</p>
  
  <p>So, the question is, why is it so hard to incorporate a BOOLEAN column while designing a relational database? Am I missing something, or is it just pushed down the to-do list as unimportant, since you can use another column type meanwhile?</p>