First, OracleOracle Server has Oracle Instace and Oracle Database
Instance is composed of memory structure and background process.
Memory structure includes shared pool, SGA (System Global area).
The SGA includes: Database buffer cache and Redo log
Kill Oracle Online users and use root to execute this script on Oracle's serverParameter description for this Oracle user
Copy Code code as follows:
#!/bin/sh
function _oracleplus () {
Su-oracle-c "$oraclehome/bin/sqlplus/nolog" Connect/
The following summarizes the MySQL conversion Oracle several points of attention, I hope to help.
1. Automatic growth of data type processing
MySQL has an automatically growing data type, and the data value is automatically obtained when you
In the development process, often encountered a number of tests, this time will want to understand the process of testing, and then based on the process to analyze the code is wrong, in this case, you need to use a custom exception, you need to know
This article content B-tree (B-tree) hashing (hash) k-d tree (k-d) dot four fork tree (Point Quadtree)
This article describes the structure of the Oracle index. Understand the data structure at the bottom of the Oracle index to better understand
Table query:
Merge query: Use the Union keyword to remove duplicate rows that meet the criteria.
Copy Code code as follows:
Select Ename,sal,job from emp where sal > 2500 Union Select ename,sal,job from emp where job = ' MANAGER ';
Problem Description: When creating a view under Scott's user, error: Insufficient permissions.
(Other users, etc.)
Workaround :
Log on as a DBA user
[SQL]
Copy Code code as follows:
Sqlplus/as SYSDBA
Give Scott user permission to
Description: The following operating environment in CentOS 6.4 + Oracle 11GR2 (Oracle installed in Oracle_base=/opt/oracle, oracle_home=/opt/oracle/11g)
After the Oracle database is installed and configured with Oui, Oracle opens (including:
Similar to other database systems, Oracle string concatenation uses the "| |" string concatenation, which is used in the same way as the plus sign "+" in MSSQLServer.
For example, execute the following SQL statement:
Copy Code code as
The content of this article• Software Environment• Simple demonstration of Oracle database concurrency causing row-level locksThis article provides a simple demonstration of row-level locks that are caused by concurrency for table primary keys.
There are two ways:
One is declaring a system cursor, one is declaring a custom cursor, and then the following action, the parameter type is
In out or out
(1) Declare a personal system cursor. Recommended
Copy Code code as follows:
Accidentally heard of the Oracle database snapshot, the word I had a listen to be stunned, do not know what this is, and then spent a little time to study the next, the following is my summary of learning through the network
Snapshots are primarily
First understand the concept of the scheme, and then understand the relationship between the scheme and the database.
Let's take a look at their definition:
Copy Code code as follows:
A
schema is a collection of the database
Oracle SQL execution Flowchart _sql execution process
First, the execution steps of the SQL statement:1 grammar analysis, the analysis of the syntax of the sentence is consistent with the norms, measuring the meaning of the expressions in the
Yesterday found in the program data analysis results are not, after the analysis, the original data is still, the value of the field is cumulative. Heart said, not Ah, is to regenerate records before the analysis of AH. Did you forget to delete it?
Mysql:
MySQL database implementation paging is relatively simple, providing a limit function. Generally, you just need to write directly to the SQL statement.The limit clause can be used to limit the amount of data returned by the SELECT statement.
It is easy to implement the automatic growth of inserting data in SQL Sever, but it is not easy to do this in an Oracle database, And you want to be in. NET to get the ID of the newly inserted data, and not to read the error, it is even more
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