Concept: Constraints

We have a number of constraints on our table and we really should understand what they do at a deeper level. In this video we'll dive into the constraint code below.

<span class="hljs-keyword">create table</span> inms(
  id bigserial <span class="hljs-keyword">primary key</span>,
  created_at <span class="hljs-type">timestamp</span> <span class="hljs-keyword">not null</span>,
  altitude <span class="hljs-type">numeric</span>(<span class="hljs-number">9</span>,<span class="hljs-number">2</span>) <span class="hljs-keyword">not null</span> <span class="hljs-keyword">check</span>(altitude <span class="hljs-operator">&gt;</span> <span class="hljs-number">0</span>),
  source text <span class="hljs-keyword">not null</span> <span class="hljs-keyword">check</span>(source <span class="hljs-keyword">in</span>(<span class="hljs-string">&#x27;osi&#x27;</span>,<span class="hljs-string">&#x27;csn&#x27;</span>,<span class="hljs-string">&#x27;osnb&#x27;</span>,<span class="hljs-string">&#x27;osnt&#x27;</span>))
  mass <span class="hljs-type">numeric</span>(<span class="hljs-number">6</span>,<span class="hljs-number">3</span>) <span class="hljs-keyword">not null</span> <span class="hljs-keyword">check</span>(mass <span class="hljs-operator">&gt;=</span><span class="hljs-number">0.125</span> <span class="hljs-keyword">and</span> mass <span class="hljs-operator">&lt;</span> <span class="hljs-number">100</span>),
  high_sensitivity_count <span class="hljs-type">int</span> <span class="hljs-keyword">not null</span> <span class="hljs-keyword">check</span>(high_sensitivity_count <span class="hljs-operator">&gt;</span> <span class="hljs-number">0</span>),
  low_sensitivity_count <span class="hljs-type">int</span> <span class="hljs-keyword">not null</span> <span class="hljs-keyword">check</span>(low_sensitivity_count <span class="hljs-operator">&gt;</span> <span class="hljs-number">0</span>)
);