Classification of Data Center reconstruction systems and data center reconstruction Systems

Source: Internet
Author: User

Classification of Data Center reconstruction systems and data center reconstruction Systems

During this time, I was truly on the machine room. After constantly overcoming the feeling that I was not satisfied with the VB. NET language, I finally had a very intuitive understanding of the reconstruction of the individual data room. This system is the same as the function of the last data center. It also checks the learning status of the data center. After reading the information about the data center, I think this figure is quite in line with my understanding of the data center.

During data center reconstruction, the focus is on the interaction process between the system and the database. At the same time, in this system, we also need to consider the code normalization and normalization during system development, applying the knowledge we learned in the C/S process to Data Center reconstruction is to test our learning achievements.

To sum up the gains of this period, we will classify the functions of data center reconstruction to facilitate the clarification of the entire system. The following is a query diagram. In this figure, some similar functions are summarized. These functions all implement the query function for the database system. Of course, some of them need to return some values, and some are to return the entire table, however, the general functions are similar.

Syntax of the SQL statement that implements the query function:

SELECT <column name or column expression of the target table>

FROM <basic table name or view sequence>

[WHERE <row condition expression>]

[Group by <column name sequence> [HAVING <GROUP condition expression>]…]

The conditions in [] on the condition are dispensable. From here, we can see that the query we normally use is very simple, and many functions need to be explored through practice. Ps: * is used to query all fields in a condition.

If you have mastered the query of SQL statements, the core issue of the query function will be solved. Others are nothing more than using VB. NET and other syntaxes for modification and logical judgment, and the above functions account for 1/4 of the entire system. It can be seen that Data Center reconstruction is an advanced learning process for us.

The following functions are added to the data center reconstruction system:

Syntax of the SQL statement that implements the Add function:

Insert into <basic table name> [(<column name sequence>)]

VALUES (<tuples>)

In this syntax, INTO is sometimes omitted, which is not a formal practice. The SQL database recognizes INSERT, but it does not necessarily recognize other databases. Omitting it during encoding may affect code reuse.

In addition, the SQL syntax is updated:

UPDATE <basic table name>

SET <column name >=< value expression>

WHERE <conditional expression>]

Delete SQL Syntax:

Delete from <basic table name>

WHERE <conditional expression>]

After mastering these four basic SQL syntaxes, the difficulties and difficulties in programming and development are much smaller.

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