[BUG] JSQLParser 4.7: ADD COLUMN IF NOT EXISTS not supported #1875

Always check against the Latest SNAPSHOT of JSQLParser and the Syntax Diagram

Failing SQL Feature:

• Brief description of the failing SQL feature

• Example: Encountered unexpected token: "IF" "IF" can't be parsed

• run java `static void buildCCJSqlParser() throws IOException, JSQLParserException {

    final Path path = Paths.get("/Users/xxx/xxx", "xxx-xxx-comm.sql");
    final byte[] bytes = Files.readAllBytes(path);
  
    ExecutorService executorService = Executors.newSingleThreadExecutor();
  
    final CCJSqlParser ccjSqlParser = CCJSqlParserUtil.newParser(new ByteArrayInputStream(bytes), StandardCharsets.UTF_8.name());
    final Statements statements = CCJSqlParserUtil.parseStatements(ccjSqlParser, executorService);
  
    final int[] updateCounter = {0};
    final int[] alterCounter = {0};
    final int[] selectCounter = {0};
    StatementVisitorAdapter adapter = new StatementVisitorAdapter(){
        @Override
        public void visit(Update update) {
            final String name = update.getTable().getName();
            final String schemaName = update.getTable().getSchemaName();
  
            updateCounter[0]++;
            System.out.printf("Update: table:%s, schema:%s%n", name, schemaName);
        }
        @Override
        public void visit(Alter alter) {
            final String name = alter.getTable().getName();
            final String schemaName = alter.getTable().getSchemaName();
  
            alterCounter[0]++;
            System.out.printf("Update: table:%s, schema:%s%n", name, schemaName);
        }
    };
    statements.accept(adapter);
  
    System.out.println(updateCounter[0] + ", " + alterCounter[0] + ", " + selectCounter[0]);
  

  }`

SQL Example:

• Simplified Query Example, focusing on the failing feature

  -- Replace with your ACTUAL example
  ALTER TABLE IF EXISTS usercenter.dict_surgeries ADD COLUMN IF NOT EXISTS operation_grade_id int8 NULL;

Software Information:

• JSqlParser version 4.7
• Database (PostgreSQL )

Tips:

Please write in English and avoid Screenshots (as we can't copy and paste content from it).
Try your example online with the latest JSQLParser and share the link in the error report.
Do provide Links or References to the specific Grammar and Syntax you are trying to use.