Inactive between database and webpage?

Let us say, I want to perform data analysis (average income of a large population), and randomly select some person as sample.
There are two tables (Income & Error) in database. Questionnaire data is manually entered into table Income.
A program is designed to clean the table Income data. If the questionnair can be fixed, then fix it. If it cannot be fixed, leave it as it is.

• Person 111/112/113/114: All of them do not answer the questionnaire properly/correctly.
• Person 111/113/114: After running the program, their data is fine now.
• Person 112: The data cannnot be fixed, it cannot be included for data analysis.
• Person 115: Original data is clean already, so it does not show up in table Error.

As mentioned above, the original data is manually entered into table Income. If it is changed to internet data collection, that being said, there will be webpage to collect data, something like online survey.
Now here are three questions:

1. When person clicks Submit button on webpage, how to transfer webpage input data into database table Income? What knowledge/what programming language is needed to learn?
2. After clicking Submit button, how to automatically trigger the program to run on the his/her submitted data? What skill is needed for this step?
3. If the submitted data is not clean, how to pull error message from table Error and display the error message on the webpage? What skill/what programming language is needed? For person 111/112/113/114, I prefer to display error message for all of them, and let every one to submit clean data only.

I want something like online credit card application process: if application form data is good, then the application can be successfully submitted, and data will be transferred to database table; if applicant form data is not good, then applicant needs to fix the data, then submit again, until application form data is clean.