1
vote
1answer
1k views

Can a Wallet be used with SQL Developer? How?

I have a Wallet configured and working fine for SQLPlus. Is there a way to make it work with SQL Developer?
66
votes
14answers
120k views

How can I move a database from one server to another?

How can I move MySQL tables from one physical server to another? Such as this exact scenario: I have a MySQL server that uses innodb table and is about 20GB size. I want to move it to a new server, ...
7
votes
4answers
2k views

For a MySQL query, how do you determine physical and logical I/O?

I'm used to having a showplan in Microsoft SQL and have gotten lazy with using tools to tune MySQL queries. How can I determine physical/logical I/O for a query in MySQL? (EXPLAIN shows the index ...
3
votes
1answer
490 views

Is there a way to allow a proxy connection to use passed authentication in a public database link?

I think the answer to this is no, but I could be wrong. If nothing else it might be nice for others to be aware of this limitation of proxy connections.
6
votes
2answers
566 views

Can Oracle be installed on Windows without being an administrator?

Can the oracle software be installed on windows without having administrator privileges?
12
votes
1answer
381 views

Best practices for connecting DBs that are in different geographical regions

We are about to set up SQL Servers in different countries. We need to link them, but we don't have to have a direct link (as in linked server). In other words, they can be loosely coupled. Is it ...
1
vote
1answer
529 views

What does HSJOIN mean in an Explain Plan?

I have the following EXPLAIN PLAN results from a query on my DB2 database. 0 SELECT STATEMENT ( Estimated Costs = 5.928E+02 [timerons] ) 1 RETURN 2 HSJOIN 3 [O] ...
27
votes
8answers
25k views

What is the difference between an INNER JOIN and an OUTER JOIN ?

I am new to SQL and wanted to know what is the difference between those two JOIN types? SELECT * FROM user u INNER JOIN telephone t ON t.user_id = u.id SELECT * FROM user u LEFT OUTER JOIN ...
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 ...
23
votes
4answers
2k views

How do you test for race conditions in a database?

I try to write database code to make sure that it's not subject to race conditions, to make sure that I've locked the correct rows or tables. But I often wonder: Is my code correct? Is it possible to ...
4
votes
1answer
240 views

Are there tools for SQL-Server helping to add the semicolons?

Earlier versions of SQL-Server didn't recommend the use of semicolons to terminate sql-statements. Beginning with sql-server-2008 examples show, that now Microsoft recommends terminating with ...
50
votes
5answers
16k views

When should I use a unique constraint instead of a unique index?

When I want a column to have distinct values, I can either use a constraint create table t1( id int primary key, code varchar(10) unique NULL ); go or I can use a unique index create table t2( id ...
3
votes
3answers
660 views

How can I use an ETL?

I know that those letters mean Extract, Transform, and Load. But, when I used it at first, I thought that during the Transform phase I could do plenty of different joins on data that I've extracted ...
29
votes
7answers
903 views

How should deletions be handled in the database?

I'd like to implement an "undelete" feature in a web application such that a user can change her mind and recover a deleted record. Thoughts on how to implement this? Some options I've considered are ...
60
votes
5answers
6k views

Do stored procedures prevent SQL injection?

Is it true that stored procedures prevent SQL injection attacks against PostgreSQL databases? I did a little research and found out that SQL Server, Oracle and MySQL are not safe against SQL injection ...
35
votes
6answers
33k views

What are the main causes of deadlocks and can they be prevented?

Recently one of our ASP.NET applications displayed a database deadlock error and I was requested to check and fix the error. I managed to find the cause of the deadlock was a stored procedure that was ...
7
votes
1answer
1k views

What's the maximum number of tables that can be referenced in a query in MySQL?

In the days of SQL Server 2000 and 2005, the maximum number of tables in a query was 256. Does MySQL have a similar limitation? I know that such query of such size means that either there's ...
19
votes
5answers
7k views

What are some ways to implement a many-to-many relationship in a data warehouse?

The dominant topologies of Data Warehouse modelling (Star, Snowflake) are designed with one-to-many relationships in mind. Query readability, performance, and structure degrades severely when faced ...
17
votes
2answers
593 views

Get and Put performance testing on Google BigTables (and other integrated DBs)

What are some effective ways to perform programmatic performance testing on database operations, especially in environments where the databases themselves do not offer dedicated tools? For example, ...
5
votes
3answers
269 views

Do higher normalized forms always meet the criteria of lower ones?

For example, a database that is 3NF is always 1NF and 2NF; does this hold for 4, 5, and 6?
7
votes
3answers
2k views

How to log data changes in Access at the table level?

I support an Access database for a non-profit organization. We have some issues with data mysteriously changing, and there been some, um, friendly debate over whether this is caused by users who are ...
3
votes
1answer
331 views

Using CoreData on a client-side application

This may be a bit more of an SO question, but... If I'm writing a client-side application for OS X that's going to sync with an online MySQL database, is there any difference on if I have CD use ...
14
votes
2answers
19k views

How can I change the default storage engine in phpmyadmin?

I use InnoDB almost exclusively in my applications. However, if I'm not careful when setting up the table, I forget to change it and phpmyadmin sticks me with MyISAM. Is there a way to change the ...
15
votes
6answers
283 views

Securing DB passwords

Looking at the structure of most PHP/MySQL-based websites I've seen, it appears that it's not terribly difficult to discern the database password if you dig a bit, as there's invariably a setup or ...
6
votes
3answers
266 views

What does the output of a JOIN statement look like?

I've been wanting to use joins for a while, but I'm having trouble visualizing the output so I know how to put it to use. Let's say I have 2 tables: CREATE TABLE Cities ( id INT UNSIGNED PRIMARY ...
8
votes
3answers
2k views

MySQL LDAP authentication

Is LDAP authentication and authorization in MySQL possible? What are the requirements (MySQL version, third-party software etc.)? How it's organized? Thanks.
6
votes
6answers
1k views

Alternative Database Tools for Web Admin [closed]

I currently use phpmyadmin for most of my database administration. It works well enough, but I'm interested in other tools that might work more quickly/efficiently/etc... What are the best and/or ...
5
votes
1answer
388 views

Oracle Support Tips & Tricks

How can My Oracle Support (Metalink) be used effectively? What are your secret hints to this system? What saved you the most time?
7
votes
3answers
5k views

Mnesia: advantages and differences

What are the advantages of Mnesia over major SQL database implementations and how it differs to them? Can I use the database to hold really huge amounts of data without noticeable performance ...
7
votes
2answers
5k views

ORDER BY using custom priorities for text columns

This is a sample table: name | cat ---------- hugo | sal bob | mgr mike | dev jeff | mgr john | dev Both name and cat being Varchar. cat reflects a category for these names, but I like to assign ...
15
votes
12answers
4k views

Comfortable sqlplus interface?

I found sqlplus'interface is rather outdated. It's quite nice to have some commands or keywords at disposal, but for example no "arrow-up" key for the previous history entry is available. What is a ...
13
votes
4answers
33k views

How to find the latest SQL statements within the database?

I like to get the latest executed statements within my database, along with performance indicators. As such, I like to know, which SQL statements were most CPU/DISK intensive.
4
votes
1answer
5k views

How can I query names using regular expressions?

How could I search for a specific pattern in a column? For example, I like to get all user names that start with either letter A or B. (btw: this is tagged oracle, but it might be interesting in ...
10
votes
2answers
4k views

Normalization Exercise Resources

I want to sharpen my database normalization skills. Where can I find good quality beginner-to-advanced level exercises (with solutions) on the web ?
14
votes
1answer
1k views

Limits of SQLite

How far can one take the sqlite database from a single-user , embedded , prototype oriented db engine ?
8
votes
2answers
903 views

How much “Padding” do I put on my indexes?

How do you know how much "Padding" an index should have?
8
votes
2answers
423 views

Biological Sequences of UniProt in PostgreSQL

What is the best way to store UniProt biological sequences in PostreSQL? Data Details We pull in 12 million sequences from UniProt - this number is likely to double every 3-10 month. The length of ...
25
votes
4answers
1k views

Is there a “best-practices” type process for developers to follow for database changes?

What is a good way to migrate DB changes from Development to QA to Production environments? Currently we: Script the change in a sql file and attach that to a TFS work item. The work is ...
32
votes
2answers
9k views

NULL or NOT NULL by default?

In MySQL, is it better to always allow nulls unless you know a field is required, or always use Not Null unless you know a field will contain nulls? Or doesn't it matter? I know in some DBMSs they ...
8
votes
2answers
977 views

How to structure a model to properly and efficiently represent tree-like data on relational databases?

Based on Traversing tree-like data in a relational database using SQL question, I would like to know how the way regularly used to describe tree-like data on relational databases considering physical ...
55
votes
8answers
18k views

When to use NULL and when to use an empty string?

I'm interested mainly in MySQL and PostgreSQL, but you could answer the following in general: Is there a logical scenario in which it would be useful to distinguish an empty string from NULL? What ...
61
votes
6answers
33k views

How to determine if an Index is required or necessary

I've been running an auto-index tool on our MS SQL database (I modified a script originating from Microsoft that looks at the index statistics tables - Automated Auto Indexing). From the stats, I now ...
8
votes
2answers
2k views

In Google App Engine, what is the most effective many-to-many join model?

The BigTable design rejects many of the philosophies of standard relational models, explicitly preferring denormalization to a big host of tiny tables. One of the larger areas where this is a problem ...
12
votes
1answer
224 views

What are the performance implications of polymodels versus normal BigTable models in google app engine?

What produces the best performance in regular google app engine use, a polymodel or a normal "BigTable" model? The polymodel, effectively, creates a column in the parent table called "class" which ...
17
votes
2answers
1k views

CouchDB vs MongoDB [closed]

Evaluating document-oriented storage, what are the pros and cons of CouchDB vs MongoDB?
15
votes
3answers
4k views

Traversing tree-like data in a relational database using SQL

Is there a way to traverse tree data in SQL? I know about 'connect by' in Oracle, but is there another way to do this in other SQL implementations? I'm asking because using 'connect by' is easier ...
28
votes
5answers
6k views

Downgrading from SQL Server 2008 to 2005

Database files that are built using SQL 2008 are not compatable with 2005. Is there a work around?
21
votes
4answers
3k views

What does “index” mean on RDBMSs? [closed]

I use indexes like most developpers do (mostly on... well ! index), but i'm sure there is a lot of subtle way to optimize a database using index. I'm not sure if it is specific to any implementation ...
15
votes
4answers
3k views

How to create a conditional index on MySQL?

How to create an index to filter a specific range? AFAIK it's impossible to create directly but I think it's possible simulate this feature. Example: I wanna create an index for NAME column just to ...
10
votes
5answers
5k views

Are there any MySQL Benchmarking tools? [closed]

I've heard a long time ago that there is this tool that helps you tweek mysql settings for better performance but i can't seam to find it. I am aware that I can use ab for apache to simulate high ...

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