Oracle

1. Define constraints when you build a table, either at the column level or at the table level. For a NOT NULL constraint, it can only be defined at the column level and cannot be defined at the table level. (1) Column-level definition Grammar:

1, the concept of authority Permissions (privilege) are rights that execute specific types of SQL commands or access other schema objects, including system permissions and object permissions. 2, the Classification of authority 1 system privilege

CREATE OR REPLACE FUNCTION fun_account_change (headobject in Ebsheadobject,           &NBS P                inaccountno in Pub_account_info. Accountno%type,                           INACC Ounttype in Pub_account_info. Accounttype%type,          

This article describes an example of using a temporary table to resolve table conflicts in Oracle, with an example of creating a temporary table Platform: Windows SP3 server Database: Oracle 9.0.1.1.1 Site Description: Users complain that not

In the analysis of the relationship between V$tempfile and V$sort_usage, we notice that Oracle's allocation rules and regular data files are not the same for the absolute file number (AFN) of the temporary file. In fact, the absolute file number of

We have recently taken into account the fact that our database-side write stored procedures are used in temporary tables, as we are not yet clear on what the database end is dealing with? Is the same way as SQL Server, there are some problems, and

First, Prepare knowledge: Oracle's logical storage management. Oracle is divided into 4 granularity on logical storage: tablespaces, segments, extents, and blocks. (1) Block: Is the smallest granularity of storage units, now the standard block

The purpose of this article: 1. Say something about Oracle's optimizer and its related knowledge. 2, answer why sometimes a table of a field is clearly indexed, when the observation of some SQL execution plan, found that the problem does not go to

Partitioning pruning Partitioning pruning means that for partitioned tables or partitioned indexes, the optimizer can automatically extract the partitions that need to be scanned from the from and where words according to the partitioning key, thus

System Global area is a huge shared memory region that is seen as a large buffer pool for Oracle databases, where data can be shared by various processes in Oracle. Its size view statement: Sql> select * from V$SGA; V$sgastat, V$buffer_pool

Because Oracle does not support the update or delete from statement, Oracle's Multiple Table association update and delete must be supported by subqueries, and, similarly, Oracle does not support simultaneous update or delete multiple tables,

In a large database system, there are two important functions, that is, stored procedures and triggers. In a database system, both stored procedures and triggers are accomplished through a collection of SQL statements and control process statements.

What happens when SQL Server Oracle MySQL detects that a value is null in the database? 1, Mssql:isnull () Grammar ISNULL (Check_expression, Replacement_value) Parameters Check_expression An expression that will be checked for null.

When solving a customer performance problem, come across an interesting SQL statement. First create a test environment: Sql> CREATE TABLE T as SELECT rownum ID, a.* from Dba_objects A, dba_queues B; Table created. sql> ALTER TABLE T ADD

To test the creation of a data guard environment on the same server. The main library is in a normal state and there are available backups, and the force logging and associated initialization parameters for the main library are set below: sql>

1. Cross-efficacy Rman backup In the case where the Rman catalog and the physical backup destination are not synchronized, we can use the Crosscheck command to verify that the Rman information in the control file or recovery directory is the same

Attempts to logically recover OCR devices have led to problems with inconsistent OCR status. Perform the following actions on one of the nodes of the RAC: bash-2.03#/data/oracle/product/10.2/crs/bin/ocrconfig-export/export/home/oracle/ocr.log

Eight Copy Introduction to 8.1 image replicas RMAN can create database data files, archive redo logs, or exact copies of control files. The Rman copy is a copy of these files, and the difference is only in the name and location changes. We don't

1, logical backup and physical backup differences 1 Physical Backup: Backup data files and control files, backup the physical structure of the entire library, mainly for media recover 2 logical backup: Back up the data structure and data of the

Some time ago in a migration of data pump and exp, found that the difference in efficiency is quite large. Here is an example of a simple comparison. This article describes ways to improve the efficiency of IMPDP import. The test in the previous