Database Administrator

The primary key id is returned when MySql is updated, and the primary key id is returned by mysql. Recently, when I was working on a project, I encountered a logic that the id of the record needs to be returned when I modify a single record. Let's

The Oracle Database row_number () over collects statistics on the first 15 enterprises, wm_concat (case when then) Row-to-column conversion, and oraclewmconcat 1.Basic usage syntax of the ROW_NUMBER () OVER function: ROW_NUMBER () OVER (partition

An example describes Oracle Any subquery and oracleany subquery. Problem:Query the names, jobs, and salaries of employees with lower salaries than any salesperson ("SALESMAN") in the Emp table.Analysis:The salesperson has many records in the Emp

Coalesce and coalesce There is such a demand. There are several contacts in the community. If there is a power outage, first notify contact 1. If not, then notify contact 2; otherwise, notify contact 3. Create table test (Id number,Name varchar2 (20

Number of record set elements and number of elementsAuthor:Www.gudianxiaoshuo.comThis article is organized by the Code Assistant Software and released content is irrelevant to this software.More comfortable reading, more comfortable writing, and

MYSQL ibdata1 space full processing, mysqlibdata1Disk Space cleaning of MYSQL server in Chengdu2.7.1 project nameChengdu Project2.7.2 Problem Description90% disk space2.7.3 impact ScopeScheduled downtime2.7.4 Problem AnalysisThe disk space of the

Oracle creation-stored procedures and functions, and oracle creation of Stored Procedures -- Create a stored procedure Create or replace procedure xxxxxxxxxxx_p (-- Parameter IN indicates the input parameter, -- OUT indicates the output parameter,

Ora-00054: resource busy and acquire with nowait specified solution, ora-00054nowait When a database user inserts, updates, or deletes data from a table in a database, or adds a table's primary key, or the table's index, a ora-00054 often occurs:

Rowid and Oraclerowid in Oracle Each table in Oracle has a rowid, which is an 18-character string, for example, AAANgBAABAAAO/KAAA. it contains a string consisting of A-Z, a-z, 0-9, +. yes. Where the A-Z corresponds to 0-25, a-z corresponds to 26-51,

MySQL DISTINCT, mysqldistinct DISTINCT (COL) is used to remove duplicates from results. For example, the table content is as follows: Select distinct (id) FROM yww_test The following example shows how to select data that has not

Oracle Gateway11g R2 access to heterogeneous databases (MSSQL) configuration document-graphic details, gateway11gmssql Directory1. Prerequisites 2. Download transparent gateway 3. Unzip and install transparent gateway 4. Configure tnsnames 5.

How to change the default value of SQL Server database column attribute is 0, sqlserver2000-- If the field has no default value, run the following statement to add the default value:Alter table name add default (1) for field name-- If the default

A few tips on SQL and SQL Preface: after a previous project was completed, the database and system architecture was designed, the system was put online on schedule after a period of coding with the brothers, and everything was running well at the

Mysql cpu usage is high. Now the game has opened the Thai server, and found that the cpu usage of the Thai server is always much higher than that of traditional Chinese or Mainland, and each time it occupies more than 300% Top-15:34:06 up 222 days, 2

Oracle instr function usage and (oracle uses instr to replace like), oracleinstr Oracle instr function appeared in the recent project, so I found some information about it on the Internet. Usage of INSTR and SUBSTR in Oracle INSTR usage in

Hibernate-tree ing and hibernate treeTree Map Hypothesis: The structure of a table is as follows: Id Parent_id Name       The company's organizational structure is tree-like ing Example: Package com. zgy. hibernate.

Set the password after installing Mysql in Linux. After Mysql is installed in Centos, the root password is not used by default. The default password is press Enter, You need to change the password for convenience. If there is no password for

Use of TTL in ssdb and use of ssdbTTL[Nerd @ QA tools] $./ssdb-cli-p 8999Ssdb (cli)-ssdb command line tool.Copyright (c) 2012-2014 ssdb. io'H' or 'help' for help, 'q' to quit.Server version: 1.8.0Ssdb 127.0.0.1: 8999> TTL 01: 00000:

Oracle Performance Optimization Operation 15th: function-based index requires equality matching and oracle Performance Optimization In the previous blog examples, we have created a function-based index, but if you execute the following query:

Oracle performance optimization operation 18: determines whether to use full table scan or index. oracle Performance Optimization Like all tips, the last trick will go back to the starting point. Finally, let's discuss whether to create an index,