FlyingZC opened a new issue, #27078:
URL: https://github.com/apache/shardingsphere/issues/27078

   # Background
   Hi community,
   This issue is for #26878.
   
   ShardingSphere parser engine helps users parse a SQL to get the AST 
(Abstract Syntax Tree) and visit this tree to get SQLStatement (Java Object). 
Currently, we are planning to enhance the support for Oracle SQL parsing in 
ShardingSphere.
   
   More details:
   
https://shardingsphere.apache.org/document/current/en/reference/sharding/parse/
   
   # Task
   This issue is to support more oracle sql parse, as follows:
   ```sql
   CREATE OR REPLACE VIEW hr_po_tab OF XMLType 
     ELEMENT "PurchaseOrder" WITH OBJECT ID DEFAULT AS
     SELECT XMLtransform(OBJECT_VALUE, x.col1)
       FROM purchaseorder p, xsl_tab x;
   ```
   
   ```sql
   CREATE OR REPLACE VIEW time_c AS
   (SELECT * FROM edge_time
   UNION ALL
   SELECT '2001-13_2', 2001, 5, '2001-05', 13, '2001-13', null, null,
   8 -- <gid_of_mon>
   FROM DUAL);
   ```
   
   ```sql
   CREATE OR REPLACE VIEW v1 AS
     SELECT *
       FROM employees
       WHERE employee_id < 150;
   
   CREATE OR REPLACE VIEW v2 AS
     SELECT v1.employee_id employee_id, departments.department_id department_id
       FROM v1, departments
       WHERE v1.department_id = departments.department_id;
   
   SELECT /*+ NO_MERGE(v2) INDEX(v2.v1.employees emp_emp_id_pk)
                           FULL(v2.departments) */ *
     FROM v2
     WHERE department_id = 30;
   ```
   
   ```sql
   CREATE OR REPLACE VIEW v_emp_job_history AS
     SELECT e1.first_name, e1.last_name, j.job_id, sum(e2.salary) total_sal
     FROM   employees e1, (SELECT * FROM employees e3) e2, job_history j
     WHERE  e1.employee_id = e2.manager_id
     AND    e1.employee_id = j.employee_id
     AND    e1.hire_date = j.start_date
     AND    e1.salary = ( SELECT max(e2.salary) 
                          FROM employees e2 
                          WHERE e2.department_id = e1.department_id ) 
     GROUP BY e1.first_name, e1.last_name, j.job_id
     ORDER BY total_sal;
   ```
   
   ```sql
   CREATE OR REPLACE view v_orders AS
   SELECT l.product_id, SUM(l.quantity*unit_price) revenue, 
          o.order_id, o.customer_id
     FROM orders o, order_items l
    WHERE o.order_id = l.order_id
    GROUP BY l.product_id, o.order_id, o.customer_id;
   ```
   
   # Process
   1. First confirm that this is a correct oracle sql syntax, if not please 
ignore;
   2. Compare SQL definitions in Oficial SQL Doc and ShardingSphere SQL Doc;
   3. If there is any difference in ShardingSphere SQL Doc, please correct them 
by referring to the Official SQL Doc;
   4. Run mvn install the current_file_module;
   5. Check whether there are any exceptions. If indeed, please fix them. 
(Especially xxxVisitor.class);
   6. Add new corresponding SQL case in SQL Cases and expected parsed result in 
Expected Statment XML;
   7. Run SQLParserParameterizedTest to make sure no exceptions.
   
   # Relevant Skills
   1. Master JAVA language
   2. Have a basic understanding of Antlr `g4` file
   3. Be familiar with Oracle SQLs


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