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14
votes
3answers
38k views

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: ╔══════════╦══════════╗ ║ ...
14
votes
2answers
14k views

For absolute performance, is SUM faster or COUNT?

This relates to counting the number of records that match a certain condition, e.g. invoice amount > $100. I tend to prefer COUNT(CASE WHEN invoice_amount > 100 THEN 1 END) However, this is ...
10
votes
2answers
724 views

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 ...
12
votes
2answers
3k views

Is there an execution difference between a JOIN condition and a WHERE condition?

Is there a performance difference between these two example queries? Query 1: select count(*) from table1 a join table2 b on b.key_col=a.key_col where b.tag = 'Y' Query 2; select count(*...
8
votes
3answers
5k views

ORA-04031: unable to allocate bytes of shared memory (“”,“”,“”,“”)

I am receiving this error in a development database. It happens on some specific queries (simple inserts and deletes via .NET application). The database is used by one user, and error happens ...
11
votes
1answer
17k views

Duplicate an Oracle database user

We'll be having external auditors coming over to perform a review on our Oracle database. They will be running a tool to perform the review and for that, they require a user ID that can connect to the ...
3
votes
3answers
2k views

Move Complete ORACLE from one system to another

I have 2 identical server with exact disk partitions (OS CENTOS 6.4 both ) [My college central oracle server]. Entire ORACLE HOME ( bin , control files, data files everything on oracle) is on 2nd ...
6
votes
4answers
1k views

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 ...
24
votes
2answers
5k views

How to make a transition from SQL Server DBA to Oracle?

As an interest, if I would to transition from a SQL Server DBA to Oracle what will be the major learning or unlearning that I would have to do? I would assume the concepts are the same and the ...
24
votes
2answers
4k views

As a DBA, how would I go about transitioning from Oracle to SQL Server?

I'm an Oracle DBA that also has Sybase experience. What are the major architectural and conceptual differences between the two RDBMS platforms? An answer similar to the SQl Server->Oracle question ...
36
votes
5answers
89k views

Difference between database vs user vs schema

I'm really confused with the terms database, user and schema. Can anyone explain how they are different from each other (if they are)? If they are same then, what are the similarities between them? ...
22
votes
8answers
21k views

How do you version your Oracle database changes?

I am interested to know what methods other people are using to keep track of changes made to the database including table definition changes, new objects, packages changes, etc. Do you use flat files ...
14
votes
4answers
135k views

How do I generate a tnsnames.ora file to connect to an Oracle Database?

I have installed Oracle 11g, and I can connect as sysman to the Oracle database, but there is no tnsnames.ora file that I can find. Do I need to generate the tnsnames.ora file myself? If so, where do ...
16
votes
6answers
15k views

Oracle Creating ER Diagrams and Data Dictionaries

I am new to Oracle Databases and would like to develop a data dictionary and ER Diagrams for our existing databases. Do you have any tips, scripts, tools for doing so?
9
votes
2answers
43k views

What is the easiest way to move data from Oracle to SQL Server?

One of our products supports both Oracle and SQL Server as database backend. We have a customer who wishes to switch from an Oracle backend to Microsoft SQL Server, which isn't a typical transition ...
1
vote
1answer
18k views

Resolving ORA-01033 “initialization or shutdown in progress”

I followed the instructions at http://www.oracle-base.com/articles/10g/oracle-data-pump-10g.php to create a database export. I used: expdp scott/tiger@db10g full=Y directory=TEST_DIR dumpfile=...
3
votes
0answers
968 views

Unable to open/connect to Oracle 12c Enterprise Manager Express

I have a just installed a new single instance installation of Oracle 12c (12.1.0.2.0 on Windows x64) with ASM. The database itself is working OK (can be accessed locally and remotely via port 1521), ...
2
votes
1answer
887 views

“Unable to display page” with Oracle 12c Enterprise Manager Database Express

i'm using redhat 6, installed 12.1.0.2 of oracle and created a database. database (dev12ee1) is a non-container database, there is also an 11g database on the server (dev11ee1) lsnrctl status shows ...
1
vote
0answers
3k views

How to run ORACLE 12C EM?

I have installed and created a database in oracle 12c in ubuntu 14.04 . Now I can login to the CLI using sqlplus \ as sysdba and run sqlcommands , but I can't login to the EM from the web. The name ...
1
vote
0answers
4k views

Start Oracle 12c enterprise manager in Windows 7

I have installed Oracle 12c in Windows 7. The installation was succesful and the RDBMS and the database that I created are working properly. Then I tried to access to the enterprise manager via web ...
1
vote
2answers
4k views

Oracle 12c Express Enterprise Manager on Centos 6.5 is not reachable

I have Centos 6.5, and installed Oracle 12c. As dbca utility says after configuring new db, EM Express should be available on https://hostname:5500/em In fact, it is not. Neither on localhost nor by ...
3
votes
2answers
30k views

ORA-12505: TNS:listener does not currently know of SID given in connect descriptor

Couple of days back, I execute shutdown on my DB but it took very long time so I shutdown my m/c. After restarting my machine, I get this exception when I try to connect to my database using TOAD. I ...
3
votes
3answers
5k views

How can I select rows from a hierarchical query with the lowest level?

I have a hierarchical query in Oracle 11gR2 that returns something like this: Parent (Level 1) Child (Level 2) Grandchild (Level 3) Child (Level 2) Grandchild (Level 3) Grandchild (Level 3) ...
1
vote
1answer
365 views

How do I import data into oracle 11g r2 using a `.dmp` file and a `.par` file?

How do I import data into a new installation of oracle 11g r2 using a .dmp file and a .par file? Here is what I have done so far, on a Windows 8.1 devbox: 1.) Open command line as administrator 2.)...
26
votes
3answers
44k views

What is the difference between sys and system accounts in Oracle databases?

There are two ways to connect to Oracle as a administrator using sqlplus: sqlplus sys as sysdba sqlplus system/manager These accounts should be uses for different purposes, I suppose. Which tasks ...
13
votes
3answers
156k views

How to make sqlplus output appear in one line?

I have a table with 100 columns. When selecting data in SQL Plus the output wraps, making it difficult to read. What I'd rather like is either a horizontal scroll bar to appear or somehow send the ...
25
votes
5answers
121k views

How to select the first row of each group?

I have a table like this: ID | Val | Kind ---------------------- 1 | 1337 | 2 2 | 1337 | 1 3 | 3 | 4 4 | 3 | 4 I want to make a SELECT that will return just the ...
20
votes
7answers
101k views

Import a Oracle DMP file into a Fresh install of oracle

A client sent us an Oracle database we need to test against. We don't use Oracle or have any in-house Oracle expertise. We need to setup the database so we can connect to it and debug a problem. I ...
20
votes
7answers
19k views

Oracle - Any way to view uncommited changes to a particular table?

I'm debugging through a batch process currently that does a lot of DML statements, but doesn't do a commit right away. It would be nice to be able to view the "pending" changes from another session ...
18
votes
5answers
188k views

How to update a table from a another table

I have one table A has column (id, field_1,field_2), and another table B has column (id,field_2) Now I want to merge table B to A, that means i want to update field_2 in table A to value of table B. ...
12
votes
1answer
87k views

How to transfer data using expdp and impdp commands?

I'm Oracle noob, and my intention is to transfer all data and metadata from one schema to another schema within an Oracle database. I'm planning to use datapump expdp and impdp commands. I have ...
13
votes
2answers
1k views

forensically deleting/updating data

I have a need to forensically remove data from oracle. If I just delete it, my understanding is the data will still actually be in the data file until that space is reused. I'm not concerned about the ...
7
votes
2answers
2k views

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 ...
8
votes
3answers
2k views

Database backups in Oracle - Export the database or use other tools?

One of the "practices" that I've seen about being performed by DBA's in my organization is to treat a full database export using tools like exp / expdp as backup. Would this be a good practice ? What ...
6
votes
4answers
17k views

Building Dynamic Oracle Where Clause

I'm working on application that uses dynamic query to do a select statement based on user input, after discussing security with DBAs they want me to convert my dynamic select statement into Stored ...
4
votes
1answer
7k views

Update oracle sql database from CSV

I tried google at first but no luck. Is it possible to update tables from csv file? I am using SQL developer and I am using a script to export edited rows to a csv file. I would like to update the ...
12
votes
3answers
6k views

How do indices impact query performance?

Obviously keeping several different indices has a negative impact on insert and delete performance. How about query performance: Does it make sense at all keeping too many indices on a table? Will the ...
10
votes
2answers
2k views

Recovering logical space from a tablespace

I have a tablespace called DATA, and it is setup with auto-extend as false. This tablespace has two datafiles and is set up so it takes up 350 GB of physical space. A week ago I queried ...
9
votes
1answer
35k views

Importing schema to new or different tablespace

Is there a convenient way to import a schema into Oracle 11gR2 using a single new or different tablespace than where the data originated? As an example, I have exported BLOG_DATA from OLDDB, where ...
13
votes
5answers
2k views

What features of Oracle make it an attractive choice for small projects?

Given Oracle's licensing handling[a] (and, to a lesser extent, cost) I have always been wondering what the deciding factors would be for choosing Oracle over PostgreSQL or MySQL. My company is nearly ...
8
votes
2answers
3k views

What is the difference between terminating an Oracle sql statement with semicolon or with a slash on the next line?

The following two queries seem to be equivalent when executed in sql*plus: 1. select * from user_tables; 2. select * from user_tables / Is there any difference between both versions?
8
votes
2answers
6k views

Why is truncate DDL?

I have an interview question, which was asked during my interview. I answered the question, but interviewer was not so convinced with my answer. So, anyone please correct me with my understanding ? Q....
3
votes
2answers
4k views

Why does the same query run faster the second time I run it?

I noticed when running a SQL query it is faster the second time than the first. So my question is, in Oracle SQL Developer where can you see the statistics that explain this behaviour?
2
votes
1answer
2k views

ORA-12528 and ORA-12505 error on Oracle database 11g

It's been one week since I last tried to run my final project that I worked on in my last internship at some banking company. Suddenly, my webapps (Java project) in Eclipse can't start. In the log it ...
2
votes
2answers
724 views

ORA-01180 when restoring the database

I get the following error message when trying to restore the database from backup using RMAN. rman target / RMAN> set dbid=130474031 RMAN> configure device type 'sbt_tape' clear; RMAN> ...
1
vote
1answer
9k views

Mounting a database from database files copied from a previous installation

I recently had on Oracle 11g Express database crash. I have copied the .dbf files from C:\oraclexe\app\oracle\oradata\XE to another folder and reinstalled Oracle 11g Express. The files are: ...
1
vote
3answers
6k views

How do you correct a corrupted index in Oracle?

I have this ORA error in our logs: Caused by: java.sql.BatchUpdateException: ORA-01578: ORACLE data block corrupted (file # 8, block # 22921) ORA-01110: data file 8: '/data/app/oracle/oradata/MYSRVR/...
1
vote
2answers
12k views

What is the difference between Schema and Database in Oracle?

In oracle, Datafile are system files where actual data is stored.The collection to datafile make Tablespace and atlast database is collection of tablespaces Correct me if I am wrong on the concepts ...
0
votes
2answers
177 views

Unable to start Oracle database

We have a oracle database, one data file(users table space) of the instance got corrupt and another data file(containing application data) was deleted due to some issue. The database is in ARCHIVELOG ...
0
votes
0answers
229 views

Character set for 11.2 version database in oracle for sql* loader

NLS_NCHAR_CHARACTERSET AL16UTF16 NLS_LANGUAGE AMERICAN NLS_TERRITORY AMERICA NLS_CURRENCY $ NLS_ISO_CURRENCY AMERICA NLS_NUMERIC_CHARACTERS ...