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What is the purpose of creating views in DBMS for existing tablesIf we update the created view of a table will the changes be reflected in the original table always?
Wiki User
∙ 12y ago
A view is generally used to provide a subset view of a table. This can be for security or clarity. For example, you have a payroll table like so:
nameaddresscitystatezipphonesupervisorsalarylast_paycheck_dateno_demeritsnotes
And you only want to have an employee see name, address, phone number, and supervisor, then they can't see hr information. Similarly, if you have multiple tables and need only 5 or 6 fields, then you can use a view to select only those fields.
A view also has the advantage that it uses less resources on the SQL server side because the SQL code is already compiled, and (in some cases), the SQL server keeps the data references up-to-date, so as not to have to find them every time it's run.
This is a very basic overview, but covers the gist of the question.
Wiki User
∙ 12y ago
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How do you crack a password mathematically?
There are several different ways to crack a password. None of them are entirely "mathematical" per se, but here you go:If you have the password hash (and algorithm), you can use one of these methods:Brute ForceDictionaryRainbow TablesIf you only have a password prompt, then you can usually only use the first two.A brute force attack involves testing every single possible combination of letters numbers and sometimes characters (like asterisks, ampersands, etc.). This type of attack takes the longest and is the most resource-intensive attack, but it yields the highest success rate. It will go through all possible combinations within the parameters you specify. For example:abc...z12...AAabac...abaabbabcabd...The next type of attack is called a dictionary or word list attack. It takes a list of words from a file and tests each of them as a password. This attack usually is the quickest, but only works on simple passwords. Some programs, like John the Ripper, support "word mangling", which modifies words in a word list to make other possible passwords. An example of this would be testing 'password' and then 'passw0rd', with the 'o' replaced with a zero.The final type of attack, which only works if you have the hash, is a rainbow table attack. Also, only certain kinds of hashes can be cracked with rainbow tables. Salted hashes, for example, cannot be cracked with rainbow tables. Anyway, rainbow tables are large files that contain tables of passwords and their associated hashes. They must be pre-generated, but common tables can be downloaded from various websites. All you do is give the cracking program the hash and the rainbow tables, and it gives you the password. It doesn't work 100% of the time, but most tables have at least a 95% chance of success. MD5 hashes are commonly cracked using rainbow tables.I hope this answers your question, as the question was not very specific.
