Select Based On Condition In Sql

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Recent advances in SQL on Hadoop and 7 related technology sharing

The greatest fascination with large data is the new business value that comes from technical analysis and excavation. SQL on Hadoop is a critical direction. CSDN Cloud specifically invited Liang to write this article, to the 7 of the latest technology to do in-depth elaboration. The article is longer, but I believe there must be a harvest. December 5, 2013-6th, "application-driven architecture and technology" as the theme of the seventh session of China Large Data technology conference (DA data Marvell Conference 2013,BDTC 2013) before the meeting, ...

The complete collection of SQL statement operations is worth permanent collections

The complete collection of SQL statement operations deserves to be permanently stored the following statements are part of the MSSQL statement and are not available in Access. SQL classification: ddl-data Definition language (create,alter,drop,declare) dml-Data Manipulation Language (Select,delete,update,insert) dcl-Data Control Language (Grant,revoke, Commit,rollback first, briefly introduce the basic statement: 1, Description: Create number ...

SQL Server Optimization: Filter condition setting improves indexing efficiency

Setting filter conditions to improve indexing efficiency good indexes are key to SQL Server database performance, but efficient indexes are carefully designed. As we all know, a primary key is a unique identifier for a data object, and if there is no clustered index in the datasheet, the SQL Server database will create a clustered index (Clustered index) for the primary key by default in order to maintain the uniqueness of the key. Unless the user specifically specifies that the index should be created as a nonclustered index (non-clustered index). There is no doubt that we ...

Windows Azure Development Select MySQL or SQL Database

Windows http://www.aliyun.com/zixun/aggregation/13357.html ">azure currently does not directly provide MySQL database services, but there is a collaboration with CLEARDB to provide MySQL Database services, or use the Windows Azure virtual machine (Windows Server or Linux Server) service to establish your own MySQL service ...

SQL Optimization Experience Summary 34

We want to do not only write SQL, but also to do a good performance of the SQL, the following for the author to learn, extract, and summarized part of the information to share with you! (1) Select the most efficient table name order (valid only in the Rule-based optimizer): The ORACLE parser processes the table names in the FROM clause in Right-to-left order, and the last table in the FROM clause (the underlying table driving tables) is processed first, In the case where multiple tables are included in the FROM clause, you must select the table with the least number of records as the underlying table. If...

Mysql database sql statement commonly used optimization methods

MySQL database sql statement commonly used optimization methods 1. Query optimization, should try to avoid full table scan, should first consider where and order by the columns involved in the establishment of the index. 2. Should be avoided in the where clause on the field null value judgment, otherwise it will cause the engine to abandon the use of indexes and full table scan, such as: select id from t where num is null You can set the default value of num 0, to ensure that Num column table does not null value ...

"Azure Services Platform Step by step-3rd" with unarmed play to SQL Data Services (SDS)

SDS is actually very friendly and fun. In this section we will not use any programming language, the Stream cow Trojan will lead everyone, only rely on an SDK called SSDs Explorer gadget to play the SDS, familiar with and implement some of the content of the previous story. Oh, it's funny. After applying for Azure, after a long wait, you will receive a letter called do not delete! Invitation Code to Microsoft. NET Services and MICR ...

Several types of SQL connections: internal, leftist, right, full, cross connection

&http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;     SQL connections can be divided into internal, external, and cross joins. Database data: Book table ...

Detailed tutorials on how to back up and restore MSSQL databases

I. BACKUP DATABASE 1, Enterprise Manager 2, SQL statement (full backup): Backup DB database to disk= ' C: your backup filename ' II, RESTORE Database 1, Enterprise Manager 2, SQL statements: Restore database Databases from Disk= ' C: your backup filename ' below is the specific procedure: first, back up the database 1, open SQL Enterprise Manager, in the console root directory in order to open Microsoft SQL ...

Summary: Differences between Hive,hiveonspark and Sparksql

Hive on Mapreduce Hive on Mapreduce execution Process Execution process detailed parsing step 1:ui (user interface) invokes ExecuteQuery interface, sending HQL query to Driver step 2:driver Create a session handle for the query statement and send the query statement to Compiler for statement resolution and build execution Plan step 3 and 4:compil ...

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