Database Administrator

There is a project that need collecting periodically (2 months) data into one table and then exporting it as excel file. The table is a temporary table, the app do that Delete from tb_name; insert into tb_name values ..... With that method, it

Non-relational databases have developed rapidly a few years ago, and have never been engaged in similar development before. Therefore, they have started learning non-relational databases. As I chose mongodb for development, I will share my learning

Batch processing is a set of T-SQL statements in a logical unit. To divide a script into multiple batches, you can use the GO statement. 1. The GO statement must have a row. 2. The GO statement allows each batch to be sent separately to the server

Zookeeper oracle 10g CRS voting disk management ----------------- Voting disk backup recovery: -- Back up voting disk: Dd if = voting_disk_name of = backup_file_name -- Restore voting disk: If your voting disk is stored on a raw device, use

Fault description:A new RAC experiment was installed, and it was found that ora. rac2.LISTENER _ RAC2.lsnr could not be started. Check listner. ora for no exception. After manual startup, the status is UNKNOW. Crs_stop-f ora. rac2.LISTENER _

Introduction Mixer wants to provide custom routing and SQL blacklist on the proxy layer to prevent SQL injection attacks. The cornerstone of these functions is to parse the SQL statements sent by users. That is, my largest lexical analysis and

Before reading this article, please back up all your important databases. Next we will officially start the backup and restoration journey. Source: http://blog.csdn.net/dba_huangzj/article/details/22683167preface Why is backup required? The reason

Count + Distinct + Group 1. Count Query the number of American students in persons. Db. persons. find ({country: "USA"}). count () 2. Distinct Check the total number of countries in persons. Db. runCommand ({distinct: "persons", key: "country"}).

1. OverviewThere are two ways to import a MySQL database:1) Export the database SQL script first and then import it;2) directly copy database directories and files.In different operating systems or MySQL versions, the method of directly copying

Generally, rownum, that is, pseudo columns, is used to specify multiple data entries to be displayed, For example Select linename from aced where rownum However, you should note that if the retrieved data contains duplicate data, rownum

MSSQL 2008 CPU Xeon E5 2G (12 CORE) X 2 RAM 128G Case 1: while @i Test result: 1,000,000 rows time: 00:04:28 size 503 MB Case 2: insert into T1 select * from T1 Test result: 1,000,000 rows insert to Table (1,000,000 rows exist) time:

-- MySQL group sorting is the simplest SQL statement for the first N records.USE test;Drop table if exists test;Create table test (Id int primary key,Cid INT,Author VARCHAR (30)) ENGINE = MYISAM;Insert into test VALUES(1, 1, 'test1 '),(2, 1, 'test1 '

mysql> select * from test;+----+-------+------+-------+| id | name | age | class |+----+-------+------+-------+| 1 | qiu | 22 | 1 | | 2 | liu | 42 | 1 | | 4 | zheng | 20 | 2 | | 3 | qian | 20 | 2 | | 0 | wang |

This document describes the connection between the URI format and the application and the MongoDB instance. For details, refer to the official MongoDB driver. Original article: http://docs.mongodb.org/manual/reference/connection-string/#connections-

The ASKTOM website provides the remove_constants function to check the SQL running status in the shared pool. The solution is to change the query condition value to a common tag, for example: replace select * from t where object_id = 1 with select *

Master-slave replication is a feature of MongoDB databases. It uses data backup to improve database disaster tolerance. However, because master-slave replication does not automatically implement failover, MongoDB has developed a new replication mode:

FIRST_VALUE and LAST_VALUE in SQL SERVER FIRST_VALUE and LAST_VALUE See the following SQL statements: WITH testas (select 'Happy col' as name, 10 as score union all select 'Happy col' blog ', 15 union all select 'Happy col ', 20 union all select

Mysql transaction operations I have long wanted to write it. I have forgotten it. It's actually very simple. Just three commands Start transactionCommitRollback Now let's explain: Start transaction;Is the command to start

/* Delete repeated feedback table data */procedure PRO_CZW_DEL_DOU_FEEBACK as begin for rec in (select row_number () over (partition by t. ywlsh/* Specified duplicate column */order by t. id desc) as lev,/* sorting of specified duplicate columns */t.

I will summarize the series of this tutorial and refuse to reprint it without my permission. Function Description: implements the set key value Command provided by redis by modifying the source code. The new command is make key value. Note that all