[Ur] Sequences

Fri Apr 1 20:31:14 EDT 2016

Hello,

I would like to refactor some code to use a sequence instead of manually
incrementing a counter to serve as a unique db table index.

Following an example, I simply did:

...
sequence expId
...

Then when I want to increment:

...
nextId <- nextval expId;
...

I recompile, but when I execute I get the following error:

Fatal initialization error: Sequence 'uw_Portfolipro_expId' does not exist.

IS there something else that I need to do, create or initialise in order to
use sequences?

Below is my full code:

table experienceTable : { Id : int, Description : string}
  PRIMARY KEY Id

sequence expId

fun refresh () =
    rows <- queryX (SELECT * FROM experienceTable)
            (fn row => <xml><tr>
              <td>{[row.ExperienceTable.Id]}</td>
<td>{[row.ExperienceTable.Description]}</td>
              <td><form><submit action={deleteExperience
row.ExperienceTable.Id} value="Delete"/></form></td>
            </tr></xml>);
    return <xml>
      <table border=1>
        <tr> <th>Id</th> <th>Description</th></tr>
        {rows}
      </table>

      <br/><hr/><br/>

      <form>
        <table>
          <tr> <th>Description:</th><td><textbox{#Description}/></td> </tr>
          <tr> <th/> <td><submit action={addExperience} value="Add"/></td>
</tr>
        </table>
      </form>
    </xml>

(* Add a new experience *)
and addExperience experience =
    nextId <- nextval expId;
    dml (INSERT INTO experienceTable (Id, Description)
         VALUES ({[nextId]}, {[readError experience.Description]}));
    page <- refresh ();
    return <xml><body>
      {page}
    </body></xml>

(* Delete a given experience *)
and deleteExperience experienceId () =
    dml (DELETE FROM experienceTable
         WHERE t.Id = {[experienceId]});
    page <- refresh ();
    return <xml><body>
      {page}
    </body></xml>

fun main () =
    content <- refresh ();
    return <xml><body>
      {content}
    </body></xml>
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