Sql Server Default Value If Null

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

1.1: Increase the secondary data file from SQL SERVER 2005, the database does not default to generate NDF data files, generally have a main data file (MDF) is enough, but some large databases, because of information, and query frequently, so in order to improve the speed of query, You can store some of the records in a table or some of the tables in a different data file. Because the CPU and memory speed is much larger than the hard disk read and write speed, so you can put different data files on different physical hard drive, so that the execution of the query, ...

SQL used to manipulate the database is generally divided into two kinds, one is the query, which is what we call the SELECT statement, the other is to update the statement, also known as data manipulation statements. The implication is to modify the data. There are 3 statements in the standard SQL, which are INSERT, UPDATE, and DELETE. There is another REPLACE statement in MySQL, so this article uses MySQL as a background to discuss how to make updates in SQL. First, INSERT and REPLACE I ...

Intermediary transaction http://www.aliyun.com/zixun/aggregation/6858.html ">seo diagnose Taobao guest cloud host technology Hall Active Server Pages, ASP 0126 (0x8000400 5 cannot find the Include file Microsoft OLE DB Provider for ODBC Drivers (0X80040E21) ...

Intermediary transaction SEO diagnose Taobao guest Cloud host technology Lobby database optimization is a very complex task, because it ultimately requires a good understanding of system optimization. 　　Even though the system or application system does not know much about the optimization effect is good, but if you want to optimize the effect of better, then you need to know more about it. 1, the optimization of the system to run faster the most important factor is the basic design of the database. 　　And you have to be aware of what your system is going to do, and the bottlenecks that exist. The most common system bottlenecks are as follows: ...

Earlier in this chapter discussed how to use SQL to insert data into a table. However, if you need to add many records to a table, it is inconvenient to use SQL statements to enter data. Fortunately, MySQL provides methods for bulk data entry, making it easy to add data to the table. This section, as well as the next section, describes these methods. This section describes the SQL language-level workarounds. 1, the basic syntax and syntax: LOAD DATA [LOCAL] INFILE 'file_name.txt' [REPLACE ...

The recently publicly previewed Azure Redis cache is easily integrated into your Azure Web site application, where I integrate the MVC Movie sample program into Azure Redis cache and deploy it to azure Web services (Websites), about a few About 15 minutes. After the cache is imported, the program is nearly 100 times times faster than the pure database because the data that is often accessed can be obtained directly from the cache ...

Several years of work down, also used several kinds of database, accurate point is "database management system", relational database, there are nosql. Relational database: 1.MySQL: Open source, high performance, low cost, high reliability (these features tend to make him the preferred database for many companies and projects), for a large scale Web application, we are familiar with such as Wikipedia, Google, and Facebook are the use of MySQL. But the current Oracle takeover of MySQL may give us the prospect of using MySQL for free ...

php tutorial + mysql tutorial database tutorial unlimited classification code This paragraph php infinite classification code more complete, including the database is mysql, add, delete, edit, move the function, while also providing the database sql table structure // connect to the database $ link = mysql_connect ('localhost', 'root', '') or die (mysql_error ()); mysql_select_db ('class', $ link) or d ...

Fourteen make PHP beginners a big headache Summary Today for everyone to give PHP beginners a headache big summary, the following 14 questions hope for PHP beginners to help. 1, the page can not be passed variables get, post, session Automatic global variables in the latest php version is turned off, so to get over the variables from the previous page to use $ _GET ['foo'], $ _ POST [ 'foo'], $ _ SESSION ['foo']. Of course it can be ...