title: Dropping unique constraint for column in H2
body: <p>I try to drop unique constraint for column in h2, previously created as <code>info varchar(255) unique</code>.</p>
  
  <p>I tried:</p>
  
  <pre><code>sql&gt; alter table public_partner drop constraint (select distinct unique_index_name from in
  formation_schema.constraints where table_name='PUBLIC_PARTNER' and column_list='INFO');
  </code></pre>
  
  <p>But with no success (as follows):</p>
  
  <pre><code>Syntax error in SQL statement "ALTER TABLE PUBLIC_PARTNER DROP CONSTRAINT ([*]SELECT DISTI
  NCT UNIQUE_INDEX_NAME FROM INFORMATION_SCHEMA.CONSTRAINTS WHERE TABLE_NAME='PUBLIC_PARTNER
  ' AND COLUMN_LIST='INFO') "; expected "identifier"; SQL statement:
  alter table public_partner drop constraint (select distinct unique_index_name from informa
  tion_schema.constraints where table_name='PUBLIC_PARTNER' and column_list='INFO') [42001-1
  60]
  </code></pre>
  
  <p>How this constraint should be correctly removed? </p>
  
  <p>By the way:</p>
  
  <pre><code>sql&gt; (select unique_index_name from information_schema.constraints where table_name='PUBLI
  C_PARTNER' and column_list='INFO');
  UNIQUE_INDEX_NAME
  CONSTRAINT_F574_INDEX_9
  (1 row, 0 ms)
  </code></pre>
  
  <p>seems to return a correct output.</p>