Questions tagged [oracle]

All versions of Oracle database. Add a version-specific tag like oracle-11g-r2 if that context is important in the question. Do not use for Oracle products such as applications or middleware or other database products owned by Oracle, like MySQL or BerkeleyDB.

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31
votes
3answers
29k 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 ...
58
votes
4answers
36k views

What is the difference between select count(*) and select count(any_non_null_column)?

I seem to remember that (on Oracle) there is a difference between uttering select count(*) from any_table and select count(any_non_null_column) from any_table. What are the differences between these ...
21
votes
3answers
77k 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: ╔══════════╦══════════╗ ║ ...
17
votes
3answers
6k 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(*)...
18
votes
4answers
61k views

How can I unload Oracle database tables into a csv files?

I need to retrieve certain data from an Oracle 11g release 1 database and provide it as one or more CSV files. The data resides in multiple tables and/or views. All this should work via the command ...
11
votes
2answers
1k 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 ...
15
votes
2answers
95k views

“ORA-01950: no privileges on tablespace 'SYSTEM' ” : What error is it?

Earlier I created a user : SQL>create user suhail identified by password SQL>User created. SQL>Grant create session,create table to suhail; SQL>Grant Succeeded. but when I login as ...
85
votes
8answers
206k 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? ...
58
votes
5answers
313k 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 ...
17
votes
1answer
36k 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 ...
5
votes
3answers
5k 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 ...
3
votes
1answer
6k 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 ...
7
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 ...
1
vote
1answer
6k views

Restrict Oracle DB Login based on SQL Client being used

We have an application in our organization that is based on Oracle Forms 11g (on Oracle Fusion Middleware/WLS). Users have access to the application through accounts created at the database (i.e. they ...
0
votes
3answers
4k views

Update values in one table based on contents of another

Software Name: Oracle SQL Developer Version 17.2.0.188 I have three tables: orders, order_details, and products. I wanted to run a query to update units_in_stock in the products table based on ...
32
votes
9answers
34k 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 ...
39
votes
7answers
73k views

EXISTS (SELECT 1 …) vs EXISTS (SELECT * …) One or the other?

Whenever I need to check for the existence of some row in a table, I tend to write always a condition like: SELECT a, b, c FROM a_table WHERE EXISTS (SELECT * -- This is what I normally ...
22
votes
5answers
242k 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 ...
5
votes
2answers
25k views

What is the difference between Schema and Database in Oracle?

In Oracle, datafile are system files where actual data is stored. The collection of datafiles make tablespace and, at last, database is collection of tablespaces. Correct me if I am wrong on the ...
6
votes
3answers
2k views

How to store many smallish time-series in a relational DB?

Input Data Multiple Tests Beds generate measurement data of various complexity. In it's most basic form, not considering any meta-data, one measurement on a Test Bed will be a small (1 - a few ...
5
votes
1answer
11k 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 ...
4
votes
1answer
6k views

Unable to open/connect to Oracle 12c Enterprise Manager Express [duplicate]

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
2answers
8k 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
8k 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
1answer
32k 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=...
8
votes
3answers
9k 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 ...
6
votes
4answers
18k 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) ...
5
votes
3answers
19k views

Use column alias in GROUP BY

I have a query where I chain two columns. Why does the alias not work in the GROUP BY clause but in ORDER BY clause, it does work? How can I write the select correctly? SELECT KOS_VER_ID AS "...
5
votes
1answer
12k views

Why isn't oracle using an index for distinct query ?

This is the scenario SQL> exec dbms_stats.gather_table_stats(user,'TM', cascade=>true) PL/SQL procedure successfully completed. SQL> SELECT SEGMENT_NAME , SEGMENT_TYPE , BYTES / 1024 / ...
4
votes
3answers
16k 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> ...
2
votes
2answers
729 views

Trigger to get next prefixed ID: Is there a better way?

I have a projects table: +------------+-----+ | PROJECT_ID | ... | +------------+-----+ | LC000001 | | | LC000002 | | | LC000003 | | | LC000004 | | | LC000005 | | +------...
1
vote
0answers
5k 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
3answers
8k 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 ...
2
votes
1answer
3k views

Step by step establish a connection between SQL Server 2014 and Oracle 12c

I have two servers (both servers are on Windows OS): Server_A running Oracle 12c Server_B running SQL Server 2014 I want these servers to be able to see each other, so I can SELECT anything I want ...
0
votes
1answer
260 views

Oracle 11 rman db restore file corruption

First to mention that I came to the need of asking help after furious research I reattempts for about 3 weeks. I checked previous threads in Oracle community but nothing works for me. I am trying to ...
48
votes
3answers
467k 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 ...
39
votes
4answers
73k 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 ...
30
votes
2answers
8k 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 ...
32
votes
2answers
5k 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 ...
29
votes
2answers
166k views

How to transfer data using expdp and impdp commands?

I'm an 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's expdp and impdp commands. I have ...
30
votes
7answers
180k 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 ...
24
votes
7answers
36k 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 ...
19
votes
6answers
16k 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?
15
votes
2answers
2k 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 ...
13
votes
2answers
78k 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 ...
15
votes
2answers
23k 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....
13
votes
2answers
62k 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 ...
12
votes
5answers
47k views

Oracle 12c Express Enterprise Manager webpage does not load

Problem summary When browsing to the Oracle 12c EM Express webinterface, the page times-out when using a URL like: http(s)://hostname:5500/em http(s)://hostname.domain:5500/em When using a url ...
11
votes
2answers
3k 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 ...
10
votes
3answers
3k 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 ...