diff --git a/preprocessing/gml_2_spider_schema_json.py b/preprocessing/gml_2_spider_schema_json.py
new file mode 100644
index 0000000..3b929da
--- /dev/null
+++ b/preprocessing/gml_2_spider_schema_json.py
@@ -0,0 +1,257 @@
+import argparse
+import yaml
+import json
+import os
+
+from pathlib import Path
+
+
+class GmlParser:
+    def __init__(self, file_path):
+        # TODO: Catch exception here
+        with open(file_path, 'r') as f:
+            self._gml_data = yaml.load(f, Loader=yaml.BaseLoader)
+
+        # Validate data
+        tables = self._gml_data.get('schema').get('tables')
+
+        if len(tables) < 2:
+            raise Exception(
+                "GNN requires at least 2 tables. "
+                "Add a dummy table with 2 dummy columns if you have a single table in your GML.")
+
+    def _parse_column_names(self):
+        original_columns = [(-1, '*')]
+        columns = [(-1, '*')]
+
+        tables = self._gml_data.get('schema').get('tables')
+
+        for tbl_idx, tbl in enumerate(tables):
+            for col in tbl.get('columns'):
+                original_columns.append(
+                    (tbl_idx, col.get('name'))
+                )
+
+                columns.append(
+                    (tbl_idx, col.get('name').lower().replace("_", ' '))
+                )
+
+        return original_columns, columns
+
+    def _parse_column_types(self):
+        column_types = ['text']
+
+        tables = self._gml_data.get('schema').get('tables')
+
+        for tbl in tables:
+            for col in tbl.get('columns'):
+                col_type = col.get('type').lower()
+
+                if 'char' in col_type or col_type == '' or 'text' in col_type or 'var' in col_type or 'string' in col_type:
+                    column_types.append('text')
+                elif 'int' in col_type or 'numeric' in col_type or 'decimal' in col_type or 'number' in col_type \
+                        or 'id' in col_type or 'real' in col_type or 'double' in col_type or 'float' in col_type:
+                    column_types.append('number')
+                elif 'date' in col_type or 'time' in col_type or 'year' in col_type:
+                    column_types.append('time')
+                elif 'boolean' in col_type:
+                    column_types.append('boolean')
+                else:
+                    column_types.append('others')
+
+        return column_types
+
+    def _parse_primary_keys(self):
+        keys = []
+
+        tables = self._gml_data.get('schema').get('tables')
+
+        col_idx = 1
+        for tbl in tables:
+            for col in tbl.get('columns'):
+                constraint = col.get('key_constraint')
+                if constraint == 'primary':
+                    keys.append(col_idx)
+
+                col_idx += 1
+
+        return keys
+
+    def _parse_foreign_keys(self, table_names=[], column_names=[]):
+        foreign_keys = []
+
+        joins = self._gml_data.get('query_generator').get('joins')
+
+        for j in joins:
+            ref_cid, cid = None, None
+
+            table_split = j["join"].split(':')
+
+            tbl_name, col_name = table_split[0].split('.')
+            ref_tbl_name, ref_col_name = table_split[1].split('.')
+
+            table_id = table_names.index(tbl_name)
+            ref_table_id = table_names.index(ref_tbl_name)
+
+            for i, (tab_id, col_org) in enumerate(column_names):
+                if tab_id == ref_table_id and ref_col_name == col_org:
+                    ref_cid = i
+                elif table_id == tab_id and col_name == col_org:
+                    cid = i
+            if ref_cid and cid:
+                foreign_keys.append([cid, ref_cid])
+
+        return foreign_keys
+
+    def _get_foreign_columns(self, table_name, column_name):
+        ref_columns = []
+
+        joins = self._gml_data.get('query_generator').get('joins')
+
+        for j in joins:
+            table_split = j["join"].split(':')
+
+            tbl_name, col_name = table_split[0].split('.')
+            ref_tbl_name, ref_col_name = table_split[1].split('.')
+
+            if tbl_name == table_name and col_name == column_name:
+                ref_columns.append(table_split[1])
+
+        return ref_columns
+
+    def _parse_table_names(self):
+        tables = self._gml_data.get('schema').get('tables')
+
+        original_names = []
+        names = []
+
+        for tbl in tables:
+            tbl_name = tbl.get('name')
+
+            original_names.append(tbl_name)
+            names.append(tbl_name.lower().replace("_", ' '))
+
+        return original_names, names
+
+    def get_gml_schema_id(self):
+        return self._gml_data["schema"]["id"]
+
+    def convert_gml_to_schema(self):
+        schema = dict()
+
+        tables = self._gml_data.get('schema').get('tables')
+
+        for tbl in tables:
+            tbl_name = tbl.get('name')
+
+            schema[tbl_name] = dict()
+
+            for col in tbl.get('columns'):
+                col_name = col.get('name')
+
+                schema[tbl_name][col_name] = {
+                    "type": col.get("type"),
+                    "rule": col_name,
+                    "is_primary": True if col.get("key_constraint") == "primary" else False,
+                    "joinable_to": self._get_foreign_columns(table_name=tbl_name, column_name=col_name),
+                    "description": col.get("description")
+                }
+
+        return schema
+
+    def convert_gml_to_gnn_schema_reader(self):
+        schema = dict()
+
+        schema["db_id"] = self.get_gml_schema_id()
+        schema["column_types"] = self._parse_column_types()
+        schema["primary_keys"] = self._parse_primary_keys()
+        schema["column_names_original"], schema["column_names"] = self._parse_column_names()
+        schema["table_names_original"], schema["table_names"] = self._parse_table_names()
+
+        schema["foreign_keys"] = self._parse_foreign_keys(
+            table_names=schema.get("table_names_original"),
+            column_names=schema.get("column_names_original")
+        )
+
+        return schema
+
+
+def process(args):
+    output_directory = Path(args.output_directory)
+
+    print(f"Loading GML:                     {args.gml_file}")
+
+    gml_parser = GmlParser(args.gml_file)
+    table_json = gml_parser.convert_gml_to_gnn_schema_reader()
+
+    tables_json_filename = output_directory / f"{gml_parser.get_gml_schema_id()}_schema_tables.json"
+
+    print(f"Writing tables json file:        {tables_json_filename}")
+    with open(tables_json_filename, 'w') as f:
+        json.dump([table_json], f, indent=2)
+
+    # Create sql file
+    sql = get_sql(table_json, gml_parser.convert_gml_to_schema())
+    sql_file = output_directory / f"{gml_parser.get_gml_schema_id()}.sql"
+    print(f"Writing SQL file:                {sql_file}")
+    with open(sql_file, 'w') as f:
+        f.write(sql)
+
+    # Create sqlite db
+    sqlite_file = output_directory / f"{gml_parser.get_gml_schema_id()}.sqlite"
+    print(f"Creating SQLite database:        {sqlite_file}")
+    os.system(f"rm -f {sqlite_file} && sqlite3 {sqlite_file} < {sql_file}")
+
+
+def get_sql(tables_json, schema_dict):
+    list_of_tables = tables_json["table_names_original"]
+    res = ""
+    for table in list_of_tables:
+        res += make_table_statement(table, schema_dict[table])
+        res += "\n\n"
+    return res
+
+
+def make_table_statement(table_name, table):
+    statement = "CREATE TABLE `{}` (\n".format(table_name)
+    for column in table.keys():
+        text = table[column]['type']
+        if text == "STRING":
+            text = "text"
+        statement += "{} {}{}".format(column, text,
+                                      " PRIMARY KEY" if table[column]['is_primary'] else "")
+        statement += ",\n"
+
+    for column in table.keys():
+        join_columns = table[column]['joinable_to']
+        if join_columns:
+            for jcol in join_columns:
+                statement += "FOREIGN KEY ({}) REFERENCES {}({})".format(column, jcol.split('.')[0], jcol.split('.')[1])
+                statement += ",\n"
+    try:
+        statement = statement[:-2]
+    except:
+        return None
+    statement += "\n);"
+    return statement
+
+
+def get_sql(tables_json, schema_dict):
+    list_of_tables = tables_json["table_names_original"]
+    res = ""
+    for table in list_of_tables:
+        res += make_table_statement(table, schema_dict[table])
+        res += "\n\n"
+    return res
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+
+    parser.add_argument('--gml-file', '-g', dest='gml_file', type=str, required=True,
+                        help='GML file')
+    parser.add_argument('--output-directory', '-o', dest='output_directory', type=str, required=True,
+                        help='Output directory to generate files')
+    args = parser.parse_args()
+
+    process(args)
diff --git a/preprocessing/requirements.txt b/preprocessing/requirements.txt
index 2c2ee91..fe469a5 100644
--- a/preprocessing/requirements.txt
+++ b/preprocessing/requirements.txt
@@ -3,4 +3,5 @@ inflection
 pandas
 nltk
 pandas
-sqlparse
\ No newline at end of file
+sqlparse
+pyyaml
\ No newline at end of file