title: postgres create user only if not exists
body: <p>I have few CREATE user  as part of  myquery.sql files and it contains few other queries as well</p>
  <p>my file looks like this</p>
  <pre><code>CREATE USER myuser NOLOGIN;
  GRANT CONNECT on DATABSE myDataBase to myuser;
  GRANT USAGE ON SCHEAMA myschema to myuser;
  </code></pre>
  <p>I have few queries like this in the same file,  due to some reason I  need to add new queries to same file, when execute the same file again I stuck with error user already exists, and does not reach to newly added query.</p>
  <p>also I checked there is no IF NOT EXISTS kind of help for CREATE USER in postgres.</p>
  <p>so how to add the check to create a USER only if not EXISTS.</p>