FlyingZC opened a new issue, #27067:
URL: https://github.com/apache/shardingsphere/issues/27067

   # 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 TRIGGER lineitems_trigger
     AFTER INSERT OR UPDATE OR DELETE ON lineitems 
     FOR EACH ROW
   BEGIN
     IF (INSERTING OR UPDATING)
     THEN
       UPDATE orders SET line_items_count = NVL(line_items_count,0)+1
       WHERE order_id = :new.order_id;
     END IF;
     IF (DELETING OR UPDATING)
     THEN
       UPDATE orders SET line_items_count = NVL(line_items_count,0)-1
       WHERE order_id = :old.order_id;
     END IF;
   END;
   ```
   
   ```sql
   CREATE OR REPLACE TRIGGER Derived 
   BEFORE INSERT OR UPDATE OF Ename ON Emp
   ```
   
   ```sql
   CREATE OR REPLACE PACKAGE tests AS
     FUNCTION valid (x NUMBER) RETURN CHAR;
     FUNCTION valid (x DATE) RETURN CHAR;
     PRAGMA RESTRICT_REFERENCES (valid, WNDS);
   END;
   ```
   
   ```sql
   CREATE OR REPLACE TRIGGER Emp_count
     AFTER DELETE ON employees
   DECLARE
     n  INTEGER;
   BEGIN
     SELECT COUNT(*) INTO n FROM employees;
     DBMS_OUTPUT.PUT_LINE('There are now ' || n || ' employees.');
   END;
   ```
   
   ```sql
   CREATE OR REPLACE TRIGGER Employee_permit_changes
     BEFORE INSERT OR DELETE OR UPDATE ON employees
   DECLARE
     Dummy             INTEGER;
     Not_on_weekends   EXCEPTION;
     Nonworking_hours  EXCEPTION;
     PRAGMA EXCEPTION_INIT (Not_on_weekends, -4097);
     PRAGMA EXCEPTION_INIT (Nonworking_hours, -4099);
   BEGIN
      -- Check for weekends:
    
      IF (TO_CHAR(Sysdate, 'DAY') = 'SAT' OR
        TO_CHAR(Sysdate, 'DAY') = 'SUN') THEN
          RAISE Not_on_weekends;
      END IF;
    
     -- Check for work hours (8am to 6pm):
    
     IF (TO_CHAR(Sysdate, 'HH24') < 8 OR
       TO_CHAR(Sysdate, 'HH24') > 18) THEN
         RAISE Nonworking_hours;
     END IF;
    
   EXCEPTION
     WHEN Not_on_weekends THEN
       Raise_application_error(-20324,'Might not change '
         ||'employee table during the weekend');
     WHEN Nonworking_hours THEN
       Raise_application_error(-20326,'Might not change '
        ||'emp table during Nonworking hours');
   END;
   ```
   
   # 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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