Database Administrator

Dba_indexes and dba_ind_columns are required to view table index information, including the composite index script: WITH nonformat (SELECT I. index_name, I. table_name, t. column_name, t. column_position, I. uniqueness, t. table_owner FROM

Using like '%', Oracle performs a full table scan, which consumes a considerable amount of system resources. This allows you to use full-text retrieval of oracle to increase the query speed. SQL>Select*FromV $ versionWhereRownum = 1; BANNER ---

When you delete data from a table, the following error occurs: ORA-02292: Full constraint condition (UNITELE. ta_sub_referene3)-subrecord found ". If the table already has a primary key, the primary key constraint is invalid. Alter table table_name

Oracle time format conversion Exception Handling Function Create Or Replace FunctionF_FORMAT_DATE (v_date varchar2, formatVarchar) /* Time Format processing format */ Return Date As V_endDateDate; V_rn varchar2 (2 ); V_LAST_DATE

Set the primary usage of Mysql master-slave replication:1. If the master server crashes, the slave server can be directly enabled as the master server.2. You can directly lock the table read-only from the server and back up the data without

ROLLUP literally means to roll to, used in group by can play a cumulative sum role: If no ROLLUP exists, the following query sums the groups by department_id and job_id: SELECT department_id, job_id, SUM (salary) FROM employees WHERE

In Oracle 11g, in order to allow the customer to change the password of the database user within six months, the default password of the database user is valid for 180 days by default, oracle 10 Gb default database user password is no time. View

Statspack is a powerful and free performance analysis tool provided by Oracle. Use a user with sysdba permissions to log on and install the SDK. With Statspack, we can easily identify the bottleneck of the Oracle database, record the database

Explain plan is a good tool for analyzing SQL statements. It can even analyze statements without executing SQL statements. through analysis, we can know how Oracle connects to the table, how to scan the table (index scan or full table scan), and the

The following error occurs during exp export. EXP-00056: Oracle error 6550 ORA-06550: 1st rows, 41st columns: PLS-00302: the 'set _ NO_OUTLINES 'component must be described ORA-06550: 1st rows, 15th columns: PL/SQL: Statement ignored EXP-00000:

Hive stores metadata in RDBMS. There are three modes to connect to the database:1) ingle User Mode: This Mode connects to an In-memory database Derby, which is generally used for Unit Test.2) Multi User Mode: connects to a database over the network,

Because of the different versions of DB2, The Script File Syntax is also different. Even redundant spaces may cause runtime errors. In recent experiments, DB2 v9.5 and v9.7 encountered many strange problems when running the SQL files created by

The use of the Oracle learning notes package can make the functions and stored procedures clearer. At the same time, you must add the package name when calling these functions and stored procedures... /** Create and use a package Syntax:

1. Oracle Server is a data management system (RDBMS) that provides open, comprehensive, and almost perfect information management. Oracle is composed of an Oracle instance and an Oracle database. The Oracle server consists of two parts: the Oracle

After the Oracle process is KILLED, the state is set to "KILLED", but the locked resources are not released for a long time, the following error message will appear: ORA-00030: User session ID does not exist Or ORA-00031: session marked for kill In

The following is an example of the stored procedure I wrote in my project. For more information, see! /* The method for calling the stored procedure in SQLPLUS is as follows :*/ Set serveroutput on;Var C varchar2 (50 );Exec aheoms. GetSEQ ('20170', '

These background processes are optional and can be selected based on your needs. They provide some tools, but these tools are not required to run the database every day, unless you want to use them yourself (such as Job Queue ), Or you need to use

1. Install Oracle database software1) Check basic requirements (mem: 1024 M, swap: mem *. Can be skipped)Memory sizeGrep MemTotal/proc/meminfoSwap partition sizeGrep SwapTotal/proc/meminfoAdd swap PartitionCreate a partition file such as/home/swap.

Summary:Direct path insertion directly allocates space outside the high waterline, bypasses the data buffer, and directly inserts data into the data file where the table is located.Direct path insertion does not generate Redo and Undo logs and

PostgreSQL lists SQL statements in progress SELECT Procpid, Start, Now ()-start AS lap, Current_query FROM (SELECT Backendid, Pg_stat_get_backend_pid (S. backendid) AS procpid, Pg_stat_get_backend_activity_start (S. backendid) AS start,