Learn the ADO

1) Real Project vs Toy Project

2) When the user is not logged in, that is Loginwindows.showdialog ()!=true, then shutdown

3) Soft Delete

Create a isdeleted field (bit type, true/false) in the database table to identify whether the object under the record has been left out, and so on.

Note: bit type, represented in SQL with 0-false, 1-true, in. NET with bool

4) Lock User: Create a islocked field

5) MD5 encryption, salt should be written to the configuration file so that users can change their own

Extension: The information fingerprint of the beauty of mathematics

6) Gender GB: 0: Unknown sex; 1: male; 2: female: 9: No gender is stated.

7) SQL ID field in the default value attribute, can be set to a function newid (), used to automatically generate ID value

8) Database Optimization: SELECT * is weaker than the Select field

9) Download the requested resource as a string specifying the resource to download in the form of a string containing the URI:webclient+downloadstring, using the following:

public static void Downloadstring (string address)
{    WebClient client = new WebClient ();    string reply = client. Downloadstring (address);
    Console.WriteLine (reply); }
See HTTP://TECHNET.MICROSOFT.COM/ZH-CN/MAGAZINE/FHD1F0SW (vs.110). aspx

Extension part: Information fingerprint of the beauty of mathematics

Information fingerprint, mainly used for information encryption and information compression and processing, through the random algorithm (formerly von Neumann pseudo-random number generator algorithm, now for the Mason rotation algorithm) mapped to the hash table, with irreversibility.

The cookie is a kind of information fingerprint, the website uses the encrypted HTTPS, encrypts the cookie itself, the Internet encryption mainly uses the encryption-based pseudo-random number generator csprng, the common standard is MD5 or SHA-1.

The use of information fingerprint: 1) The same judgment set, mainly to the two fingerprints and the same or not to judge, can be used to determine whether it is a pirated file;

2) The judgment set is basically the same, take inverse text frequency index IDF maximum several words, calculate its information fingerprint to judge, such as Google's search plagiarism project copycat (using specific information fingerprint-similar hash-to fault tolerance);

3) YouTube anti-piracy, the video key frame extraction and feature extraction, and then as the principle, to judge.

With the key encryption, the public key is encrypted and the private key is decrypted.