Question

how can I specify a NOT NULL contraint at the end of my sql statement as I can with a UNIQUE

 CREATE TABLE test ( 
        WORKFLOW_CLASS_ID VARCHAR2(24),
        DEPT_OWNER VARCHAR2(3), 
        NAME VARCHAR2(64), 
        PRODUCT_ID VARCHAR2(24), 
        CONSTRAINT WF_WORKFLOW_CLASS_pk PRIMARY KEY (WORKFLOW_CLASS_ID), 
        CONSTRAINT dup_workflow UNIQUE (DEPT_OWNER, NAME), 
        CONSTRAINT not_null NOT NULL(PRODUCT_ID)) 

The above create string is built dynamically using schema defined in an XML document, which defines constraints in its own tag, so therefore I tack on the contraints at the end of the sql string. When I try to specify NOT NULL I get invalid identifier.

EDIT:
Below is the stucture of my xml document. This file has evolved and over time. I use it to generate DAO and Javabean boilerplate code that I cut and paste into Eclipse and for dynamically creating html forms (xml has field, size and label). It is also used for an Admin CRUD application for maintaining the backend. I recently added the <tableConstraints> tag because I wanted to add UNIQUE constraints; UNIQUE constraint could be specified at the end of the create statement. In hind sight, I should have added a <contraint> tag within my <column> tag.

<!DOCTYPE schema PUBLIC "SchemaId" "../../schema.dtd">
<schema>
  <tableName>WF_WORKFLOW_CLASS</tableName>
  <javaBean>WorkflowClass</javaBean>
  <tableAlias>wfc</tableAlias>
  <tableTitle>Workflow process definitions by department</tableTitle>
  <tableConstraints>, CONSTRAINT dup_workflow UNIQUE (DEPT_OWNER, NAME), CONSTRAINT not_null NOT NULL(PRODUCT_ID)</tableConstraints>
  <oneToMany>
        <attName>work_item_list</attName>
        <attName>work_action_list</attName>
  </oneToMany>

  <column>
        <name>WORKFLOW_CLASS_ID</name>
        <type>VARCHAR2</type>
        <size>24</size>
        <label>Work flow Class Unique ID</label>
  </column>

  <primaryKey>      
        <name>WORKFLOW_CLASS_ID</name>
        <type>timestamp</type>
  </primaryKey>

  <foreignKey>
        <name>ADMIN_BY</name>
        <table>EBITPSV.PS_NAMES_V009</table>
        <lookUpKey>badge</lookUpKey>
        <returnField>lname</returnField>
  </foreignKey>

</schema>

Answer 1

An not null constraint is declared inline, after each individual column name:

CREATE TABLE test ( ... 
        NAME VARCHAR2(64), 
        PRODUCT_ID VARCHAR2(24) not null,
        ... )

If you wish to name the constraint explicitly then you also do this after each column:

CREATE TABLE test ( ... 
        NAME VARCHAR2(64), 
        PRODUCT_ID VARCHAR2(24)  
         CONSTRAINT PRODUCT_ID_NN NOT NULL,
        ... )

You can of course modify the column after the table has been created:

ALTER TABLE test
 MODIFY product_id varchar2(24) not null;

Update:

Judging by your recently posted XML script the best thing to do would be to add a sub-tag <notNull> to your <column> tag. With 2 values – e.g. 1, 0 you could add a not null constraint in the same way as you decide whether something is a varchar or not.

The other way it would be possible is to loop through the values in your <tableConstraints> tag and run multiple alter table add constraint ... or alter table modify ... after you have created the table.

You suggestion of adding <constraint> sub-tag in <column> and creating them all at the column level will only work for single column constraints not multiple as you need here.