Oracle

  The content of this lecture includes: 1: Diagnose database performance 2: configure the automatic workload file library 3: Use a database Consultant 4: use SQL access advisor to improve database performance 5. asynchronous submission About

  After years of experience with oracle, I found myself and some people around me have some bad development and operation methods in oracle usage, which can be used for reference. I. oracle programming: 1. The oracle code writing format is not

Many friends familiar with SQL server often make a mistake when they come into contact with oracle, that is, they always think that oracle also has the structure of update from. The from statement does not exist in the update Statement of oracle. We

When I encountered a problem in the project, I searched from the Internet and thought the following explanation was easy to understand: Assume that oracle has two users: admin and visitor.We created the testtable table in admin and granted

Generally, for a database with a single function, you can set an optimizer mode at the instance level,For example, for OLAP systems, most of the time the database runs a report job, the execution is basically an aggregate SQL operation,For example,

% TYPE attributeIn PL/SQL, you can declare variables and constants as built-in or user-defined data types to reference a column name and inherit its data types and sizes. This dynamic value assignment method is very useful. For example, the data

SQL> Select count (*) from v $ session where status = 'active ';COUNT (*)----------20SQL> Select count (*) from v $ session;COUNT (*)----------187SQL> show parameter processes;NAME TYPE

JDBC inserts data into the database to obtain the primary key. Currently, I have summarized two methods: 1. Applicable to databases with auto-increment columns (such as SQL-server and mysql)/*** Insert data to obtain the primary key* @ Param annex* @

Oracle Database system is a complex software system. Without understanding its internal structure principles and relationships, it is impossible to design and Compile High-Quality application software systems or manage a complex application system.

SQL statement in Oracle time format -- 12-hour system current time (AM) SQL> select to_char (sysdate, 'yyyy-MM-DD HH12: MI: SS am') from dual; -- 24-hour system current time (PM) SQL> select to_char (sysdate, 'yyyy-MM-DD HH24: MI: SS pm') from dual;

Oracle Table query and precautions △Query the specified column (remove duplicate rows) select distinct deptno, job from emp; △name must be capitalized select deptno, job from emp where ename = 'Smith '; △ process null values using nvl function

Oracle sequence explanation and creation of auto-incrementing primary key Oracle sequence primary key sequence: a database object provided by oacle to generate a series of unique numbers. L automatic provision of unique value l shared object l

Oracle Used to delete the DBF file to clear and drop all the tables, and the file was deleted. However, the actual DBF data file still exists under the ORADATA file. Must be deleted like this Drop tablespace tablespace_name [including contents [and

Partition index (1) 1. Partition index the partition index simply divides an index into multiple segments. By dividing an index into multiple segments, you can access smaller segments (faster) and store these segments on different disk drives (to

ORACLE: plsql optimization 1. After logon, My Objects is automatically selected by default? Setting Method: Tools menu -- Brower Filters will open the order window of Brower Filters and set "My Objects" to default .? Similarly, you can move the

Learning window functions over () in OracleYou can use window functions to solve some problems. For example, if we have two tables, one for the instructor and one for the department, and if we want to query the average salary of the teachers in each

To correctly configure the tnsname. ora file, you can use the Oracle Net Configuration Assistant or Oracle Net Manager graphical Configuration tool on the client machine to configure the client. The Configuration tool actually modifies the tnsnames.

The listener is not started or the database service is not registered with the listener solution oracle Encounters "the listener is not started or the database service is not registered with the listener" as follows: C: \ Users \ zhou> emca-repos

Was: configure the data source of the oracle RAC cluster. Configure the data source of the Oracle RAC cluster in WebSphere. Assume that the Oracle RAC double-click is HOST1 and HOST2, and the port is 1521. The service name is orcldbservice, the URL

Perform the following operations on the oracle analysis table: 1) Verify the storage status of the table 2) view the statistical information of the table 3) Search for the link record and migration record in the table 1) verify the storage status of