datasource. It exists between the data source and the business layer, encapsulating the details of access to the data, such as database connections, sending execution SQL statements, and closing the connection resources. The primary purpose of DAO is to completely separate the underlying data access operations from the high-level business logic operations, providing transparent data access services to the business layer and enhancing the flexibility of the program. The DAO component encapsulate
Conversion tool: Http://tool.oschina.net/encrypt?type=4 directly using the IMG can be replacedIMG SRC does not connect local address implementation output a picture (using base64)
rules:
SOCKFD can be written when the connection is established.
When an error is encountered, the SOCKFD is both readable and writable.
We set a time-out period when poll returns, and if SOCKFD is writable, there are two things at this time:
One is that the connection does build up successfully
Second, the connection error occurred
We need some means to tell if something is wrong.Here we use the socket option, the detection is So_error,
connection multiplexing and control, rather than to use this method of the problem)How is the Q:access-log table maintained?A: Because it is a log system, it is recommended to use the archive storage engine, which facilitates data compression and storage. If the number of database connections is large, it is recommended to do a data export for a certain time, and then clear the table.Q: Does the table have other uses?A: there! The Access-log table is of course not only for auditing, but also fo
This article describes the Android programming implementation setting, the way to open a WiFi hotspot to share for others to connect to. Share to everyone for your reference, specific as follows:
Friends who use fast teeth should know that they are using a WiFi hotspot when transferring files between two days of equipment, and then another connects to the hotspot for transmission. The speed of the fast too
This article illustrates the Java implementation JSP's approach to using Servelt to connect Oracle databases. In order to connect a database in a servlet, you must write a servlet class program. To place the Servlet class program under the Servlets or classes directory of the Web server, to invoke the servlet, you need to create an HTML document that sends a serv
Tags: desc from Oracle Log div recursive class sel withRecursion:SELECT *From t_pams_solution tStart with t.id is nullConnect by prior id = t.parent_idORDER BY level DESCThe red characters are the table name, the start condition, the child node and the root association condition respectively.Reverse recursion:Select RowNum num,Level Lev,Connect_by_root (ID) ID,Connect_by_root (solution_name) nameFrom t_pams_solution twhere t.id = 23379Start with 1 = 1Connect by prior id = t.parent_idORDER BY lev
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