Sql Set Multiple Columns

Designing 1 applications doesn't seem to be difficult, but it's not easy to achieve the optimal performance of the system. There are many choices in development tools, database design, application structure, query design, interface selection, and so on, depending on the specific application requirements and the skills of the development team. This article takes SQL Server as an example, discusses the application performance optimization techniques from the perspective of the background database, and gives some useful suggestions. 1 database design to achieve optimal performance in a good SQL Server scenario, the key is to have 1 ...

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. The operation of data and log files stored separately on different disks for data files and log files produces a large amount of I/O. 　　Where possible, the log file should be stored on a hard disk that is different from the data file where the data and index are located to distribute I/O, while also facilitating disaster recovery for the database. 2.tempdb databases are stored on separate disks the tempdb database is a temporary database that all other databases are likely to use. When you use SELECT INTO to execute the by by on a column that is not indexed ...

1, use the index to traverse the table faster. The index created by default is a non-clustered index, but sometimes it is not optimal. Under non-clustered indexes, the data is physically stored on the data page. Reasonable index design should be based on the analysis and prediction of various inquiries. In general: a. There are a large number of duplicate values, and often range query (>, <,> =, <=) and order by, group by occurred columns, consider the establishment of cluster index; Column, and each column contains duplicate values ​​can be ...

1, use the index to traverse the table faster. The index created by default is a non-clustered index, but sometimes it is not optimal. Under non-clustered indexes, the data is physically stored on the data page. Reasonable index design should be based on the analysis and prediction of various inquiries. In general: a. A large number of duplicate values, and often range query (>, <,> =, <=) and order by, group by occurred column, consider the establishment of cluster index; b. Column, ...

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 ...

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In the new field of Big data, BigTable database technology is well worth our attention because it was invented by Google, and Google is a well-established company that specializes in managing massive amounts of data. 　　If you know this well, your family is familiar with the two Apache database projects of Cassandra and HBase. Google first bigtable in a 2006 study. Interestingly, the report did not use BigTable as a database technology, but ...

Cassandra and HBase are the representatives of many open source projects based on bigtable technology that are implementing high scalability, flexibility, distributed, and wide-column data storage in different ways. In this new area of big data [note], the BigTable database technology is well worth our attention because it was invented by Google, and Google is a well-established company that specializes in managing massive amounts of data. If you know this very well, your family is familiar with the two of Cassandra and HBase.

Through the introduction of the core Distributed File System HDFS, MapReduce processing process of the Hadoop distributed computing platform, as well as the Data Warehouse tool hive and the distributed database HBase, it covers all the technical cores of the Hadoop distributed platform. Through this stage research summary, from the internal mechanism angle detailed analysis, HDFS, MapReduce, Hbase, Hive is how to run, as well as based on the Hadoop Data Warehouse construction and the distributed database interior concrete realization. If there are deficiencies, follow-up ...