To write in text file

See aqFile.WriteToTextFile Method. When you have a new text file, it's not possible to write to a specific line, as the file is empty. And for an existing text file, use ReadLine Method to skip the number of lines, and then write the text.

You will have to create your own function, to write to a specific line in a text file.

Do we have any database query to append data to database using automation script in test complete

What do you mean exactly? Can you elaborate please?

If we want to add any data to the database so for that we need a database query, But I need to do this using an automation script using test complete. So do you know about this.

See Working With Databases and the examples. 

The post went from a text file to a database query ?