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8
votes
3answers
2k views

Should date formats be specified in SQL statements?

I see code from developers using implicit date conversion. I would like a definitive answer to why they should not do this. SELECT * from dba_objects WHERE Created >= '06-MAR-2012';
8
votes
6answers
6k views

Is Oracle free to download?

I am a Java developer and currently I use PostgreSQL as the RDBMS. However, I would also like to learn Oracle. So can I download a latest version of Oracle (11g I guess) for free? I found this link: ...
8
votes
5answers
24k views

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 ...
8
votes
2answers
12k views

Why do we need to backup Oracle archive logs along with datafiles

Oracle® Database Backup and Recovery Basics 10g Release 2 (10.2) says that Archived redo logs are the key to successful media recovery. Back them up regularly. But, I wonder, why backups of ...
8
votes
8answers
171k views

Connect to sql plus from command line using connection string

Let's say I have a Oracle database. I have a username = x, password = y, database = z. Also I know the port = a, SID = b, Hostname = c. So how do I need to connect correctly? I used many options ...
8
votes
3answers
6k views

I have a powerful machine with 70 GB RAM. How many Oracle instances with 20 GB can be created?

I have powerful machine with 70 GB RAM. I created one Oracle instance with 20 GB as sga_target. I am not able to create another Oracle instance with sga_target > 10G even when I keep the ...
8
votes
5answers
5k views

Oracle sort varchar2 column with special characters last

How can I sort in Oracle a Varchar2 or NVarchar2 column to be in my own custom defined order. Or are any existing options available that will put letters first, then numbers, then all special ...
8
votes
4answers
12k views

Feature comparison: Oracle Database and Microsoft SQL Server [closed]

Many companies have a heavy influence on market and technologies around them, and you often compare the products before you choose, e. g. I liked Oracle APEX, its flexibility and features, and we're ...
8
votes
1answer
45k views

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 ...
8
votes
1answer
1k views

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 & ...
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
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 ...
8
votes
4answers
305 views

What would I need to do to make sure my DB policies have to pass a security audit?

I have an audit coming up, and I was wondering what physical, electronic, and logical access controls an auditor would look for when auditing a database for an ERP system. I'm really new to this ...
8
votes
1answer
28k views

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 ...
8
votes
3answers
6k views

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 ...
8
votes
2answers
687 views

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 ...
8
votes
2answers
133 views

SQL Server equivalent of Oracle USING INDEX clause

Is there a SQL Server 2008 equivalent of the USING INDEX clause in Oracle? Specifically for the construct: CREATE TABLE c(c1 INT, c2 INT); CREATE INDEX ci ON c (c1, c2); ALTER TABLE c ADD CONSTRAINT ...
8
votes
2answers
8k views

How to retrieve foreign key constraints data

I'm looking for a query allowing to retrieve foreign key infos (each line: referrencing table & field, referrenced table & field) of an entire schema. I've found this, but does not gives all ...
8
votes
2answers
21k views

How do I find an object that doesn't seem to exist in the objects table?

I have an object called cot_ntn_pi_v. I was told this was a synonym. It doesn't appear in the all_synonyms table. It looks like a view or table but I can't find it in the all objects table. I can ...
8
votes
2answers
3k views

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 ...
8
votes
1answer
20k views

How can I import the contents of an Oracle database into Visio to create an Entity Relationship Diagram?

I have an Oracle database, and I would like to create an ERD in Visio 2007 Pro. I have so far looked at DBMS_METADATA.GET_DDL commands to generate DDL. I know that I can import an Access DB into ...
8
votes
1answer
4k views

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 ...
8
votes
2answers
7k views

What specifically does OracleBulkCopy do, and how can I optimize its performance?

To summarize the specifics: We need to stage approximately 5 million rows into a vendor (Oracle) database. Everything goes great for batches of 500k rows using OracleBulkCopy (ODP.NET), but when we ...
8
votes
2answers
2k views

How to migrate SQL Server Stored Procedures using temporary tables or table variables to Oracle?

C# developer encouraged by management to write SQL Server stored procedures often produce procedures like this create table #t1 (...); insert into #t1 Select ... from table_a where ...; insert into ...
8
votes
1answer
564 views

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 ...
8
votes
1answer
612 views

How can a datapump export have its resource usage limited on linux?

Doing an export of a number of users causes high CPU and I/O usage. I can mitigate the effects of the CPU usage using Resource Manager and setting the export session to a low priority group, but how ...
8
votes
2answers
8k views

How to Install/Configure Oracle Instant Client on Ubuntu

Installing the Oracle Instant Client on Ubuntu/Debian based systems is awkward since Oracle is RPM centric regarding its Linux support. What's the best way to easily install and configure the Instant ...
8
votes
2answers
5k 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 ? ...
8
votes
2answers
366 views

How to modify an update in Oracle so it performs faster?

I have this query: UPDATE ( SELECT h.valid_through_dt, h.LAST_UPDATE_TMSTMP FROM ETL_FEE_SCH_TMP d, FEE_SCHEDULE_HISTORICAL h WHERE h.FUND_ID = d.FUND_ID AND ...
8
votes
1answer
17k views

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 ...
8
votes
3answers
259 views

Unexpected CASE evaluation logic

I always understood that the CASE statement worked on a 'short-circuit' principle in that evaluation of subsequent steps does not take place if a prior step is evaluated to true. (This answer Does SQL ...
8
votes
1answer
328 views

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 ...
8
votes
1answer
680 views

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. ...
8
votes
1answer
572 views

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 ...
8
votes
1answer
2k views

Use LDAP for name look up with Oracle Instant Client

Partly as a result of having problems with conflicting versions or bitness with the full installation of Oracle client, my development team (of which I'm a member) has been moving towards using Oracle ...
8
votes
0answers
230 views

9i streams capture doesn't evaluate rules

I have a streams replication set up between two oracle 9.2.0.8 instances as sources and an 11g instance as a destination, processing a small subset of data from each database (let it be one table ...
7
votes
5answers
10k views

Auto-Commit in SQL Server and Oracle

When I worked on Oracle 8 many years before, I used to execute COMMIT command manually after each bulk INSERT. In SQL Server, Auto-Commit is ON by default which has advantages as well as hazards. I ...
7
votes
4answers
22k views

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) ...
7
votes
2answers
940 views

Resources for SQL Server developer migrating to Oracle

What resources can you recommend for a SQL Server developer wanting to learn Oracle basics? I am looking for a comprehensive whitepaper or blog post describing differences between these systems and ...
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 ...
7
votes
2answers
3k views

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, ...
7
votes
2answers
10k views

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 ...
7
votes
2answers
1k views

If I SET ARRAYSIZE 1 in SQL*Plus, the records are still fetched in pairs. Why?

I thought about writing a simple tail -f like utility to "trace" the progress of some figures within the database: create or replace function tail_f return varchar2_tab pipelined as n number; ...
7
votes
1answer
102k views

“ORA-03113: end-of-file on communication channel” on startup

I have been reading posts here, on Oracle support, and anywhere else I can find for the last three days and I've given up on this problem... An Oracle database hung. Shutdown of the database sat for ...
7
votes
2answers
45k 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 ...
7
votes
4answers
806 views

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 ...
7
votes
2answers
373 views

In Oracle, can we restore a database onto the same instance with a different name?

In SQL server I can restore a database onto the same instance with a different name. Eg: If there is a database DB_prod, I can take a full backup and restore it on the same instance with a different ...
7
votes
2answers
23k views

sqlnet.ora or tnsnames.ora changes require reboot?

Anytime you change Oracle's sqlnet.ora or tnsnames.ora files, does the system require a reboot? In my instance, I only have the Oracle client installed on the machine I'm referring to, but out of ...
7
votes
3answers
2k views

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) ); ...
7
votes
2answers
4k views

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 ...