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:

CREATE TABLE docs (
    docid    NUMBER, 
    pub_date DATE, 
    author   VARCHAR2(30), 
    category VARCHAR2(30), 
    document CLOB
);

CREATE TABLE emp_load (first_name CHAR(15),
                      last_name CHAR(20),
                      year_of_birth INT,
                      phone CHAR(12),
                      area_code CHAR(3),
                      exchange CHAR(3),
                      extension CHAR(4))
  ORGANIZATION EXTERNAL
  (TYPE ORACLE_LOADER
   DEFAULT DIRECTORY ext_tab_dir
   ACCESS PARAMETERS
     (FIELDS RTRIM
            (first_name (1:15) CHAR(15),
             last_name (*:+20),
             year_of_birth (36:39),
             phone (40:52),
             area_code (*-12: +3),
             exchange (*+1: +3),
             extension (*+1: +4)))
   LOCATION ('info.dat'));

CREATE TABLE emp_load (first_name CHAR(15), last_name CHAR(20),
year_of_birth CHAR(4))
  ORGANIZATION EXTERNAL (TYPE ORACLE_LOADER DEFAULT DIRECTORY ext_tab_dir
                         ACCESS PARAMETERS (FIELDS LTRIM)
                         LOCATION ('info.dat'));

CREATE TABLE emp_load (first_name CHAR(15), last_name CHAR(20), year_of_birth CHAR(4))
  ORGANIZATION EXTERNAL (TYPE ORACLE_LOADER DEFAULT DIRECTORY ext_tab_dir
                         ACCESS PARAMETERS (RECORDS DELIMITED BY '|' FIELDS TERMINATED BY ','
                                              (first_name CHAR(7),
                                               last_name CHAR(8),
                                               year_of_birth CHAR(4)))
                         LOCATION ('info.dat'));

CREATE TABLE emp_load (first_name CHAR(15), last_name CHAR(20), year_of_birth CHAR(4))
  ORGANIZATION EXTERNAL (TYPE ORACLE_LOADER DEFAULT DIRECTORY ext_tab_dir
                         ACCESS PARAMETERS (RECORDS FIXED 20 FIELDS (first_name CHAR(7),
                                                                    last_name CHAR(8),
                                                                    year_of_birth CHAR(4)))
                         LOCATION ('info.dat'));

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