title: skipping liquibase change if table exists
body: <p>New to liquibase. I have an existing schema managed by hibernate. I now need to remove some tables and I'm using liquibase. I wrote a config that succesfully deletes the table.</p>
  
  <p>But I want the check to run only if the table exists, since a new install of the system would not have the table since the hibernate mapping objects no longer exist.</p>
  
  <p>I attempted to add a precondition. However, my logs still indicating that liquibase is failling becuase it tries to delete the table and it doesn't exist. What am I not doing correctly? I'm using Spring Boot / Java</p>
  
  <pre><code>databaseChangeLog:
    - preConditions:
        on-fail: mark_ran
        on-error: mark_ran
        tableExists:
          tableName: some_old_table
          schemaName: public
    - changeSet:
        id: 01_del_old_table
        author: some-dev-01
        comment: Remove old table
        changes:
          - dropTable:
              tableName: some_old_table
  </code></pre>
  
  <p>error in log: Table public.some_old_table does not exist
  ...</p>
  
  <pre><code>PreconditionFailedException
  </code></pre>
  
  <p>It's like ti's checking the preconditions... and still failing them.</p>
  
  <p>Also tried</p>
  
  <pre><code>databaseChangeLog:
    - changeSet:
        id: zzchange-1.0-remove-xczczxc
        author: zzzz
        comment: Remove some_old_table table - no longer needed
        preConditions:
          on-fail: mark_ran
          tableExists:
            tableName: some_old_table
        changes:
          - dropTable:
              tableName: some_old_table
  </code></pre>