Oracle

  % Type, % rowtype in oracle 1. Use % TYPE In many cases, PL/SQL variables can be used to store data in database tables. In this case, the variable should have the same type as the table column. For example, if the first_name column type of the

  Before you begin to explain how to use the Oracle sequence, add "/" to the use of Oracle client sqlplus, that is, if you execute multiple rows of statements, you must add "/" to end the statement and execute it! The topic of this article is to

  In ORACLE, You can automatically create a unique index when creating a primary key constraint, or create a unique index first, and then create a primary key constraint based on this unique index. The latter method has the following advantages:

1./* + ALL_ROWS */ It indicates that the overhead-based optimization method is selected for the statement block, and the optimal throughput is obtained to minimize the resource consumption. For example: SELECT/* + ALL + _ ROWS */EMP_NO, EMP_NAM, DAT_

Importing and exporting Oracle Data imp/exp is equivalent to restoring and backing up oracle data. The exp command can export data from the remote database server to the local dmp file, and the imp command can import the dmp file from the local to

Important: cursors are inefficient for large data volumes. Important:1. cursor attributes2. Current of cursor Current record  1. cursor: the cursor is the result set after select. We can use the cursor to assign each entry of the result set to the

I. Analysis Function syntax FUNCTION_NAME ( ,...) OVER ( )   1. FUNCTION_NAME ( ,...) The purpose of each analysis function is described later. 2. OVER keyword Over is just a keyword. It is an analysis function. 3. PARTITION clause The condition

Author: runming 2012-2-1 QQ: 226399587 http://blog.csdn.net/runming918 Difference between Purge and drop:The new flashback drop feature provided by Oracle 10g provides the flashback drop feature to speed up recovery of user error operations. In

Author: runming 2012-2-1 QQ: 226399587 http://blog.csdn.net/runming918 This article describes the concepts and operations of Partitioned Tables from the following aspects:1. Concepts of tablespaces and partition tables2. Specific functions of table

1. Create oracle users and tablespaces in Windows-- Create a data table spaceCreate tablespace oras_data -- Name of the tablespaceLoggingDatafile 'd: \ oracle \ product \ 10.1.0 \ oradata \ oras_data.dbf '-- storage of the tablespace file spaceSize 3

To solve the Oracle client garbled problem, the key is to unify the character set used by the server with the character set used by the client. The Oracle client (Sqlplus) uses the NLS_LANG environment variable to determine the character set used by

Manage oracle clusterware (Voting Disk) The Voting Disk file is mainly used to record the node member status. When split-brain occurs, it is determined that the Partion gets control, and other Partion must be removed from the cluster. Voting disk

Problem Background:How can the COUNT function value of the following SQL statement be larger than the number of T_1 rows and T_2 rows in the table? Is it an ORACLE database BUG?SQL:Select count (*) from t_1, t_2 where t_1.id = t_2.id and t_1.id =

CURSOR is also called a CURSOR. It is often used in relational databases. In PL/SQL programs, you can use CURSOR and SELECT to query data in tables or views and read data row by row. Oracle cursors include display cursors and implicit cursors.

Recently, the company is working on Oracle database-related products. Here is a summary:The ISNULL () function syntax ISNULL (check_expression, replacement_value) parameter check_expression will be checked for a NULL expression. Check_expression can

1. view the database size. Select pg_size_pretty (pg_database_size ('db _ name'); Through pgAdmin, we can see that PostgreSQL (pg_catalog) has the following two views: pg_stat_user_tables and pg_stat_user_indexes. You can use these to view the table

During the installation process, select create database, enter the user name, password, and so on. After installation is successful, the database is created successfully. In this case, log on through pl/SQL and select the normal logon prompt as

The syntax of the MODEL clause in oracle is as follows: MODEL [] [] [MAIN ] [partition by ()] dimension by () MEASURES () [] [RULES] (, ,.., ) www.2cto.com ::= :: = RETURN {ALL | UPDATED} ROWS :: = [ignore nav | [keep nav] [Unique dimension |

Test on slow table data deletion: recently, I was bored with my watch and found that data deletion is far from faster than query. As a result, I made an experiment. The experiment content is as follows, and the level is limited. I hope it will serve

Sequence explanation sequence in oracle: generate an integer sequence, which is usually used to fill the number-type primary key columnCreate sequence Syntax: create sequence seq_name [start with start_num] [increment by incre_num] [maxvalue max_num