Before extracting data, familiarize yourself with the PrestaShop database schema. PrestaShop uses a MySQL database, so identify the tables and fields you need to extract. Common tables include `ps_products`, `ps_orders`, and `ps_customers`.

Use SQL queries to export the required data from the PrestaShop MySQL database. You can use the command line or a tool like phpMyAdmin to execute queries and export data in CSV format. For example:
```sql
SELECT * FROM ps_products INTO OUTFILE '/path/to/export/products.csv'
FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\n';
```

Ensure your Oracle database is ready for data import. Create equivalent tables in Oracle that match the structure of the PrestaShop tables. Use Oracle SQL Developer or a similar tool to handle table creation. For example:
```sql
CREATE TABLE products (
id NUMBER PRIMARY KEY,
name VARCHAR2(255),
price NUMBER(10, 2),
...
);
```

Before importing, clean the data in the CSV files to match the Oracle database's requirements. This includes ensuring date formats are compatible, removing any unsupported characters, and ensuring numeric fields are correctly formatted.

Use Oracle's SQL*Loader utility to import the data from CSV files into the Oracle database. Create a control file that defines how SQL*Loader should interpret the CSV file. For example:
```plaintext
LOAD DATA
INFILE 'path/to/export/products.csv'
INTO TABLE products
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
(id, name, price, ...)
```
Execute the SQL*Loader command:
```shell
sqlldr userid=username/password control=path/to/controlfile.ctl
```

After loading, verify the data integrity in the Oracle database. Run queries to ensure the data has been accurately transferred and no records are missing. Check for discrepancies between source and destination data.

If ongoing synchronization is necessary, script the export and import process using shell scripts or batch files. Schedule these scripts using cron jobs or Windows Task Scheduler to automate regular data transfers.

By following these steps, you can efficiently move data from PrestaShop to an Oracle database without relying on third-party connectors or integrations.