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Third, the existing O/R mapping product introduction O/R mapping has been a long time, a lot of products: Java has hibernate, JDO and so on. Net has objectspaces, grove.net, Ojb.net, Atomsframework, Objectz.net, OPF. NET and so on. 1, Hibernate

Example Description: (1) Create 2 table spaces first. Create tablespace user01 datafile ' +dg1 ' size 1M; Create tablespace user02 datafile ' +dg1 ' size 1M; (2) Create a table on each table space. CREATE TABLE Scott.customers (cust_id

Oracle First chapter: Log Management 1.forcing Log Switches sql> alter system switch logfile; 2.forcing checkpoints Sql> alter system checkpoint; 3.adding Online Redo Log groups sql> ALTER DATABASE Add logfile [Group 4] Sql> ('/disk3/log4a.rdo ',

Js In any web-based application, the program logic requires the user to submit information that needs to be validated, and the creator of the application can detect the data in two ways. The first approach is to validate on the client, even before

1, select the most applicable field properties MySQL can support a large amount of data access, but generally speaking, the smaller the table in the database, the faster the query executed on it. Therefore, in order to achieve better performance

A friend mentioned a data pump import problem, in the presence of a table, do not delete the table, and import the table's data and indexes. In fact, this task is very simple for imp, because IMP works in this way. sql> CREATE TABLE T_exp 2 (ID

Oracle First week: Flash back query Get a movie instead of a picture: Flash back version query No setting required to immediately recognize all changes to a row In the Oracle9i Database, we saw that it introduced a "time Machine" in the form of

Transaction processing is one of the most important problems to be solved in enterprise application. Java EE provides complete transaction management capabilities through JTA, including the ability to manage multiple transactional resources. But

Use of the 1.having clause The HAVING clause controls the row groups determined by the GROUP BY clause, which only allow constants, clustered functions, or columns in the GROUP BY clause to be involved in the condition of the HAVING clause. 2. Use

Many database operations on the web require transactions, and there are roughly 3 levels of transactions under ASP.net: (1) Transaction at the level of the stored procedure (2) Ado.net-level transactions (3) asp.net transaction at the page

1. After installing the DB2 database, you can use the command line or graphical interface to operate, if your database server is not on this computer, you need to be in the "Client Configuration Helper" in the configuration of a client connection. 2

In the morning to the office to listen to colleagues said the table was locked, a try, found that a table in a field of 1111111 of the row are locked, select None. Report Error ORA-01591, open toad knowledge EXpert, described very little, just say

Data | database | Database connection A database buffer pool refers to a physical connection to a database that is cached in memory space, and these database connections can be reused. The database buffer pool is important for improving the

Skills Next:ASP Development 44 Skills Collection of the second 1. Several common functions Round (pi, 2) roundedFormatNumber (k,4) ' formats K as a number with four-bit decimal points.eg. If K =20000 is shown as 20,000.00 if FormatNumber (k,0) is 20,

The following code has been tested to run directly Oracle analysis functions, multidimensional functions and model functions are briefly described, mainly for the BI report statistics, not necessarily very comprehensive, but a little explanation of

Whether you need to rebuild the index regularly is a topic that DBAs have been arguing about, never stopping. Summarize the views of the parties ---5.1 Reasons to support rebuilding indexes 1 Oracle's B-tree index becomes unbalanced over time Many

Blocking occurs when the first connection from the application controls the lock and the second connection requires a conflicting lock type. The result is to force the second connection to wait while blocking on the first connection. A connection

Resolution | control | Issues on the Forum see the question http://community.csdn.net/Expert/topic/3772/3772658.xml?temp= the CustomValidator control verifies that the control value is empty. 9461634, just as I have encountered, the solution is not

Server|sqlserver first, starting from the error in SQL Server, there are some strange error-handling errors at the same level as 16 but the results are different. SELECT * from an absent table if @ @error print ' This has no output ' Go

Creates a transactional object on a database connection, and then invokes a transaction object to commit the transaction or rollback the transaction. Simple code: PRivate void Button1_Click (object sender, System.EventArgs e) { SqlConnection conn