title: Listing all not null constraints in a postgresql table
body: <p>I am trying to use psql in the terminal to find all nullable columns in a database. If I use</p>
  
  <pre><code>select * from information_schema.check_constraints;
  </code></pre>
  
  <p>I get information such as the following</p>
  
  <pre><code> constraint_catalog | constraint_schema  |       constraint_name        |                                         check_clause                                         
  --------------------+--------------------+------------------------------+----------------------------------------------------------------------------------------------
   foo                | public             | 12345_67890_1_not_null       | bar IS NOT NULL
  </code></pre>
  
  <p>Unfortunately, the column <code>bar</code> appears in many tables. What is the easist way I can get a list of all <code>public</code> constraints like this which list both the column names and the table names? </p>