Oracle is a RDBMS (Relational Database Management System) created by Oracle Corporation. It supports a large number of languages and application development frameworks. Its primary languages are SQL, PL/SQL and Java. Also included is support for C (Pro*C, OCI and EXTPROC), C++ (OCCI) and Java (JDBC) ...

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Where to start with Oracle?

This question only needs one answer: a list of great resources for getting started with Oracle, including Database Administration, PL/SQL and SQL. You may find your question has been closed as a ...
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Database for building a realtime analytics system

I want to build a system similar to Google Analytics (only used for internal use, less traffic and less feature), and mainly focus on Real time counting of unique URI visit/PV by different ...
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Materialized views in oracle

How are materialized views implemented in oracle? I've created a materialized view in oracle. What I now see is a quite normal table with a job. Are materialized views translated into tables & ...
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Getting “ORA-00942: table or view does not exist” while table does exist

I'm fairly new to Oracle database. I have installed Oracle Database 11g R2 on Oracle Linux 6. I have successfully created a new database with dbca and connected to the database using: $ sqlplus "/ as ...
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Multiple operations using WITH

Is there a way to execute multiple operations using the WITH statement? Something like WITH T AS ( SELECT * FROM Tbl ) BEGIN OPEN P_OUTCURSOR FOR SELECT * FROM T; SELECT COUNT(*) INTO ...
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How to extract Procedure, Function, etc. Source Code from an Oracle Export

I have generated an EXPDAT.DMP file of an Oracle database with the command: exp userid=usr/pass@db owner=own rows=n compress=n I then ran the following command to generate a file containing the ...
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What happens when you modify (reduce) a column's length?

Lets say I have two columns of type NUMBER (without precision, and scale) and VARCHAR(300). I saw that these columns are way too large for my data, so I want to modify them to NUMBER(11) and ...
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Oracle's left join and where clauses errors

CREATE TABLE "ATABLE1" ( "COLUMN1" VARCHAR2(20 BYTE), "COLUMN2" VARCHAR2(20 BYTE) ); CREATE TABLE "ATABLE2" ( "COLUMN1" VARCHAR2(20 BYTE), "COLUMN2" VARCHAR2(20 BYTE) ); ...
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How do you protect against malicious PREPROCESSOR attacks in Oracle External Tables?

I'm a new DBA and I recently found out about the option of External Tables in Oracle using the PREPROCESSOR feature ( ...
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How do you show SQL executing on an Oracle database?

How can you show the SQL that is currently executing on an oracle db? Extra information that would be useful would include user, session id etc.
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How do I declare and use variables in Oracle?

My main skills are with SQL Server, but I have been asked to do some tuning of an Oracle query. I have written the following SQL: declare @startDate int select @startDate = 20110501 And I get this ...
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Multiple Oracle Instances — is this a good practice?

One of my clients has deployed our product's db into a Solaris machine which already has 3 instances of Oracle. So, right now there are 4 instances of Oracle running on the same machine. And now we're ...
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Oracle 11g: performance improvements of inserts

I have a table of 500 millions of rows (and growing) I did the following to improve performance of inserts: On database side: dropped all indexes and constraints disabled logging On application ...
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Cardinality is so far off from reality

I've got a table where the cardinality for plans just seems waaaaaay too high - despite updating stats and even trying dynamic sampling for Oracle 11gR2. select count(*) from table1 where col1 = ...
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Is this a new common pattern in Oracle Where exists ( Select NULL FROM…)?

Years ago, it was common to write where exists (Select * from some_table where some_condition) Last year I noticed that many t-sql scripts switched to using the number 1 instead of the star where ...
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Oracle 10g: Is it possible to designate a undo point?

I was wondering if it is possible to designate a point in time, then later "roll-it-back" to that state (undo DDL and DML changes). Maybe using a record of changes and then executing the reverse? Does ...
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Why is Oracle using the index here?

Name Null Type -------- -------- --------- ID NOT NULL NUMBER(4) GROUP_ID NUMBER(4) TEXT CLOB There is a btree index on group_id. Here's how many ...
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How can I Estimate Table Sizes within Schema (Oracle)

I'm trying to estimate the table sizes within my schema (in MB). This is what I have so far: SELECT table_name, owner, last_analyzed FROM all_tables I'm fairly new to SQL so I have no idea how I ...
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Limit redo for materialized view complete refresh or manual equivalent

A materialized view(MV) log can be used to allow a MV to do a fast refresh which only modifies the data that has changed. However, various conditions prevent the MV from using the log and therefore ...
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Oracle materialized view refresh schedule

Since I see that it is possible to specify an expression like sysdate + 1, here are my questions: Is it possible to specify the exact time of the refresh for materialized views in oracle? Is it ...
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Can I use OpenLDAP to authenticate users in Oracle?

I like to use OpenLDAP to authenticate my Oracle users. It should be possible to fetch at least the password from the directory. There appearently is something for the Oracle LDAP servers, but would ...
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Tablespace on ephemeral storage

For performance reasons in some scenarios, e.g. Amazon EC2, you have access to a faster and cheaper storage device, which loses all its data on reboots, so it is called "ephemeral". This question is ...
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Map Oracle roles to Active Directory groups?

Is there any built-in way to map Oracle database roles to Microsoft Active Directory groups?
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How can I rewrite for SQL Server a trigger that writing for Oracle?

How can I rewrite for SQL Server a trigger that was originally written for Oracle ? Here is my Oracle trigger code: CREATE OR REPLACE TRIGGER P000KUL_TEST BEFORE INSERT ON P000KUL REFERENCING NEW AS ...
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What makes an Oracle Applications DBA different from an Oracle DBA?

All Oracle databases support some type of application that the Oracle DBA would need to have some knowledge of. What makes an Oracle Applications DBA different than this? Does the term mean that ...
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Temporal Validity and Primary/Foreign Key Relationships

I've read through several of the oracle tutorials that show temporal validity and time features. However, in the examples I'v read, there is no primary key used in the demo tables. ...
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Execute a script with SQLPlus containing blanks, semi-colons, and forward slashes

Occasionally I will get a script that will run fine in SQL Developer or Toad, but requires modification in order to be run successfully from SQL*Plus. Here is a worst case example containing multiple ...
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Why would function based indices I’ve created lower the cost but not show up in the explain plan breakdown?

Sorry for the terrible column/table names but since this is for a work project I wanted to insure it was OK to ask. I was just hoping to at least learn why I'm not seeing my functional indices being ...
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Generate XML using Oracle XML schema

I have some XML schema definitions that have been registered using DBMS_XMLSCHEMA. I have created tables using the XMLTypes generated. I can create XML using XMLQuery and if I understand correctly, ...
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Designing Simple Schema for Disaggregation of Demand Forecast

I am doing a simple database design task as a training exercise where I have to come up with a basic schema design for the following case: I have a parent-child hierarchy of products (example, Raw ...
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Oracle returns an error ORA-01031: insufficient privileges

Oracle returns an error "ORA-01031: insufficient privileges" When I run sqlplus / as sysdba but sqlplus sys/oracle123 as sysdba doesn't, why? Oracle version: Oracle Database 10g Enterprise Edition ...
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Pivot rows into multiple columns

I have a SQL Server instance that has a linked server to an Oracle server. There is a table on the Oracle server called PersonOptions which contains the following data: ╔══════════╦══════════╗ ║ ...
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Does an IOT guarantee order in a select?

We need to add a priority column to a table that gets hit about 250 times a second, approx 170 selects, 125 inserts and 60 updates. The column will be a simple number(1). The priority does not matter ...
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PL/SQL: best way to count elements in an array?

Given this: DECLARE TYPE T_ARRAY IS TABLE OF VARCHAR2(2000) INDEX BY BINARY_INTEGER; MY_ARRAY T_ARRAY; V_COUNT INTEGER; I would like to do: BEGIN -- ... some code filling the MY_ARRAY ...
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Is Oracle DB licensing needed for a test environment?

I'm planning to setup an Oracle Standard Edition instance on a server in our test environment. Do I need to purchase a license for this?
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Why use explicit cursors instead of regular loops?

I've been writing basic web apps for a year (for an Oracle db), and since the functions are pretty simple, most of us stick with regular FOR loops to get our data: for i in (select * from STUDENTS) ...
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Is DB2 more reliable and stable compared to PostgreSQL or MySQL?

Always i was using MySQL or PostgreSQL for my projects such as Web/Desktop apps. I had data loss few times and thanks to old backup i was always up and running. But for a recent project for Airport, ...
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How to document Oracle database?

I'm new to Oracle databases. I have used to SQL Server and the description fields (MS_Description) for tables and columns for documentation purposes. Is there an equivalent for Oracle? What is the ...
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SQL Server Express vs. Oracle Express Edition vs DB2 Express-C

I have been trying to compare the features of the SQL Server Express, Oracle XE and DB2 Express-C, but find it difficult to compile all the differences into one place. Especially the current ...
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Why Oracle sessions are still alive after two weeks being Inactive

DB: Oracle 10g O/S: Windows Server 2003 64 bits I query list of Oracle sessions generated by web applications (filter by program=w3wp.exe) select * from V$session where UPPER(program) LIKE '%W3%' ...
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Is there a need to keep refreshing the indexes from time-to-time?

This question is common for all the database products I use, viz. SQL Server, MySQL, Oracle and PostgreSQL. I have created a fresh database and the tables, at present, have no records. I have created ...
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How to get rid of ORA-28002 message the password will expire within 6 days?

I have a user getting an ORA-28002 indicating that the password will expire within six days. I ran the following: ALTER PROFILE DEFAULT LIMIT PASSWORD_LIFE_TIME UNLIMITED; But when I try to log ...
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When a record is locked in Oracle, can we know which record is locked?

When a record is locked ,can we know which one is locked? How can I get the record rowid or something else info? I can get some info by this sql SELECT ...
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How do I query to pull all data in row based MIN and MAX service date?

I'm very new to Oracle SQL especially in the Pentaho report builder. It lets you do some things and block others. PL/SQL is not available so I must do this in a query. I need to be able to pull ...
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Can this business logic be enforced by a conditional database constraint?

I am trying to duplicate the business logic embodied an intranet C# web application in the database so that other databases can access it and work under the same rules. This "rule" seems difficult to ...
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Will the Oracle optimizer still plan a join if I'm not reading any columns in the joined table?

Suppose I have the following view: CREATE VIEW dummy AS SELECT a.some_column, b.other_column FROM a LEFT JOIN b USING (key_column); When I do a SELECT some_column FROM dummy, is there a way to ...
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Clustered index in SQL Server vs index organized tables in Oracle

I am making the transition as a database developer from SQL Server to Oracle and found some fantastic resources here already (How to make a transition from SQL Server DBA to Oracle? and As a DBA, how ...
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Does it make sense to consolidate Oracle databases?

I am more experienced with SQL Server and Sybase than Oracle, and understand those products well. I've been asked to look for ways to reduce the server estate running Oracle. I understand that an ...
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Oracle 10g - How to prevent one user from hogging all resources?

I am wondering if there is any way to limit how much resources one user can take on my Oracle system. I want to limit some queries and systems from being able to hog all system resources when they run ...
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What is “SAP on Oracle”

OK, total newb question. What is "SAP on Oracle", exactly. This link is talking about how SAP can run on Oracle (I think). I'm not understanding how this is working. My understanding: SAP is a ...