simple-ddl-parser 0.7.0

Simple DDL Parser to parse SQL & HQL ddl files to json/python dict with full information about columns: types, defaults, primary keys, etc.

Simple DDL Parser

Build with ply (lex & yacc in python). A lot of samples in ‘tests/’

How to install

pip install simple-ddl-parser

How to use

From python code

from simple_ddl_parser import DDLParser


parse_results = DDLParser("""create table dev.data_sync_history(
    data_sync_id bigint not null,
    sync_count bigint not null,
    sync_mark timestamp  not  null,
    sync_start timestamp  not null,
    sync_end timestamp  not null,
    message varchar(2000) null,
    primary key (data_sync_id, sync_start)
); """).run()

print(parse_results)

To parse from file

from simple_ddl_parser import parse_from_file

result = parse_from_file('tests/sql/test_one_statement.sql')
print(result)

From command line

simple-ddl-parser is installed to environment as command sdp

sdp path_to_ddl_file

# for example:

sdp tests/sql/test_two_tables.sql

You will see the output in schemas folder in file with name test_two_tables_schema.json

If you want to have also output in console - use -v flag for verbose.

sdp tests/sql/test_two_tables.sql -v

If you don’t want to dump schema in file and just print result to the console, use –no-dump flag:

sdp tests/sql/test_two_tables.sql --no-dump

You can provide target path where you want to dump result with argument -t, –targer:

sdp tests/sql/test_two_tables.sql -t dump_results/

How does it work?

Parser tested on different DDLs for PostgreSQL & Hive. Types that are used in your DB does not matter, so parser must also work successfuly to any DDL for SQL DB. Parser is NOT case sensitive, it did not expect that all queries will be in upper case or lower case. So you can write statements like this:

Alter Table Persons ADD CONSTRAINT CHK_PersonAge CHECK (Age>=18 AND City='Sandnes');

It will be parsed as is without errors.

If you have samples that cause an error - please open the issue (but don’t forget to add ddl example), I will be glad to fix it.

A lot of statements and output result you can find in tests, for example:

test_alter_statements.py

This parser take as input SQL DDL statements or files, for example like this:

CREATE TABLE employees (
    id SERIAL PRIMARY KEY,
    first_name VARCHAR (50),
    last_name VARCHAR (50),
    birth_date DATE CHECK (birth_date > '1900-01-01'),
    joined_date DATE CHECK (joined_date > birth_date),
    salary numeric CHECK(salary > 0),
    phone_numbers varchar(16) array,
    tags varchar ARRAY[1]
);
CREATE TABLE dev.Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    City varchar(255),
    Country varchar(255),
    CONSTRAINT CHK_Person CHECK (Age>=19 AND City='Sandnes')
);

ALTER TABLE dev.Persons ADD CHECK (Age>=18 AND City='Sandnes');

ALTER TABLE dev.Persons Add CONSTRAINT ck_person  CHECK (Age>=18 AND City='Sandnes');
Alter Table dev.Persons ADD CONSTRAINT fk_group FOREIGN KEY (id) REFERENCES employees (id);
create unique index person_pk on dev.Persons (ID) ;
create index person_ix2 on dev.Persons (City, Country);

And produce output like this (information about table name, schema, columns, types and properties):

[{
  'table_name': 'employees',
  'index': [],
  'primary_key': ['id'],
  'schema': None,
  'alter': {},
  'checks': [],
  'columns': [{'check': None,
               'default': None,
               'name': 'id',
               'nullable': False,
               'references': None,
               'size': None,
               'type': 'SERIAL',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'first_name',
               'nullable': True,
               'references': None,
               'size': 50,
               'type': 'VARCHAR',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'last_name',
               'nullable': True,
               'references': None,
               'size': 50,
               'type': 'VARCHAR',
               'unique': False},
              {'check': "birth_date > '1900-01-01'",
               'default': None,
               'name': 'birth_date',
               'nullable': True,
               'references': None,
               'size': None,
               'type': 'DATE',
               'unique': False},
              {'check': 'joined_date > birth_date',
               'default': None,
               'name': 'joined_date',
               'nullable': True,
               'references': None,
               'size': None,
               'type': 'DATE',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'phone_numbers',
               'nullable': True,
               'references': None,
               'size': 16,
               'type': 'varchar[]',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'tags',
               'nullable': True,
               'references': None,
               'size': None,
               'type': 'varchar[1]',
               'unique': False}]},

    {'table_name': 'Persons',
    'index': [{'columns': ['ID'], 'index_name': 'person_pk', 'unique': True},
                {'columns': ['City', 'Country'],
                'index_name': 'person_ix2',
                'unique': False}],
    'primary_key': [],
    'schema': 'dev',
    'alter': {'checks': [{'constraint_name': None,
                        'statement': ['Age>=18', 'AND', "City='Sandnes'"]},
                       {'constraint_name': 'ck_person',
                        'statement': ['Age>=18', 'AND', "City='Sandnes'"]}],
            'columns': [{'constraint_name': 'fk_group',
                         'name': 'id',
                         'references': {'column': 'id',
                                        'schema': None,
                                        'table': 'employees'}}]},
  'checks': [{'constraint_name': 'CHK_Person',
              'statement': "Age>=19 AND City='Sandnes'"}],
  'columns': [{'check': None,
               'default': None,
               'name': 'ID',
               'nullable': False,
               'references': None,
               'size': None,
               'type': 'int',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'LastName',
               'nullable': False,
               'references': None,
               'size': 255,
               'type': 'varchar',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'FirstName',
               'nullable': True,
               'references': None,
               'size': 255,
               'type': 'varchar',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'Age',
               'nullable': True,
               'references': None,
               'size': None,
               'type': 'int',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'City',
               'nullable': True,
               'references': None,
               'size': 255,
               'type': 'varchar',
               'unique': False},
              {'check': None,
               'default': None,
               'name': 'Country',
               'nullable': True,
               'references': None,
               'size': 255,
               'type': 'varchar',
               'unique': False}]
               }]

SEQUENCES

When we parse SEQUENCES each property stored as a separate dict KEY, for example for sequence:

CREATE SEQUENCE dev.incremental_ids
INCREMENT 1
START 1
MINVALUE 1
MAXVALUE 9223372036854775807
CACHE 1;

Will be output:

[
    {'schema': 'dev', 'incremental_ids': 'document_id_seq', 'increment': 1, 'start': 1, 'minvalue': 1, 'maxvalue': 9223372036854775807, 'cache': 1}
]

ALTER statements

Right now added support only for ALTER statements with FOREIGEIN key

For example, if in your ddl after table defenitions (create table statements) you have ALTER table statements like this:

ALTER TABLE "material_attachments" ADD FOREIGN KEY ("material_id", "material_title") REFERENCES "materials" ("id", "title");

This statements will be parsed and information about them putted inside ‘alter’ key in table’s dict. For example, please check alter statement tests - tests/test_alter_statements.py

More examples & tests

You can find in tests/ folder.

Dump result in json

To dump result in json use argument .run(dump=True)

You also can provide a path where you want to have a dumps with schema with argument .run(dump_path=’folder_that_use_for_dumps/’)

Supported Statements

• CREATE TABLE [ IF NOT EXISTS ] + columns defenition, columns attributes: column name + type + type size(for example, varchar(255)), UNIQUE, PRIMARY KEY, DEFAULT, CHECK, NULL/NOT NULL, REFERENCES

• STATEMENTS: PRIMARY KEY, CHECK, FOREIGN KEY in table defenitions (in create table();)

• ALTER TABLE STATEMENTS: ADD CHECK (with CONSTRAINT), ADD FOREIGN KEY (with CONSTRAINT)

TODO in next Releases (if you don’t see feature that you need - open the issue)

1. Provide API to get result as Python Object

2. Add online demo (UI) to parse ddl

Historical context

This library is an extracted parser code from https://github.com/xnuinside/fakeme (Library for fake relation data generation, that I used in several work projects, but did not have time to make from it normal open source library)

For one of the work projects I needed to convert SQL ddl to Python ORM models in auto way and I tried to use https://github.com/andialbrecht/sqlparse but it works not well enough with ddl for my case (for example, if in ddl used lower case - nothing works, primary keys inside ddl are mapped as column name not reserved word and etc.). So I remembered about Parser in Fakeme and just extracted it & improved.

How to run tests

git clone https://github.com/xnuinside/simple-ddl-parser.git
cd simple-ddl-parser
poetry install # if you use poetry
# or use `pip install .`
pytest tests/ -vv

How to contribute

Please describe issue that you want to solve and open the PR, I will review it as soon as possible.

Any questions? Ping me in Telegram: https://t.me/xnuinside

Changelog

v0.7.0

1. Redone logic of parse CREATE TABLE statements, now they parsed as one statement (not line by line as previous)

2. Fixed several minor bugs with edge cases in default values and checks

3. Added support for ALTER FOREIGN KEY statement for several fields in one statement

v0.6.1

1. Fix minor bug with schema in index statements

v0.6.0

1. Added support for SEQUENCE statemensts

2. Added support for ARRAYs in types

3. Added support for CREATE INDEX statements

v0.5.0

1. Added support for UNIQUE column attribute

2. Add command line arg to pass folder with ddls (parse multiple files)

3. Added support for CHECK Constratint

4. Added support for FOREIGN Constratint in ALTER TABLE

v0.4.0

1. Added support schema for table in REFERENCES statement in column defenition

2. Added base support fot Alter table statements (added ‘alters’ key in table)

3. Added command line arg to pass path to get the output results

4. Fixed incorrect null fields parsing

v0.3.0

1. Added support for REFERENCES statement in column defenition

2. Added command line