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Database Design
Database design is the process of creating a detailed data model of a database. It is the next step after requirement gathering and before coding begins. A good database design can save a lot of time during the database development.
1,295 Questions
Nope. It's not illegal, so unless they have a logical explanation for shutting down, they aren't. You can try it right now; it's still up.
What is the basic structure of SQL Select statement?
select name
from (table name)
where condition
The most fundamental and common elements of a SELECTstatement, namely
- SELECT
- FROM
- WHERE
- ORDER BY
1.SELECT "column_name" FROM "table_name"
2.SELECT "column_name" FROM "table_name" where "condition"
3.SELECT "column_name1","column_name2"FROM "table_name" where "condition" ORDER BY "column_name"
Can you add new columns to a database after creating the structure?
Columns are added to a table, not a database (which is a collection of tables). Adding a column to a table is achieved by using the Alter Table SQL command.
The oerr utility (Oracle Error) is provided only with Oracle databases on UNIX platforms. oerr is not an executable, but instead, a shell script that retrieves messages from installed message files. The utility is not provided on Windows systems, since it uses awk commands to retrieve the requested text from the file.
An embedded pop is a pop up ad. These ads can be blocked by going to ad/remove programs in the control panel and check for any unknown program. If this does not work, you can block the program from appearing at start up by going to start/run and typing mscongfig and select the start up tab in the list of programs. Uncheck any entry that you do not want.
Is there a microchip in aeroplanes?
Modern aeroplanes use many microchips in their navigation systems, radio systems, climate control, engine management and other places.
What type of Data determines the quality of the data?
The data should not be redundant and should be validated. The data or records should be interrelated.
Excerpts from Microsoft Computer Dictionary (5th Edn):
.csv n. The file extension for a comma-delimited text file.
CSV n. Acronym for comma separated values. Filename extension assigned to text files containing tabular data of the sort stored in database fields. As the name indicates, individual data entries are separated by commas.
What is single database architecture?
When you architect an application that utilizes a single database rather than splitting responsibilities or rolls between two or more databases. Such division can be useful in providing a stronger isolation level and a more clear delineation in the development process.
Is it reasonable to say that problem domain components should never exhibit external coupling?
External coupling occurs when a component communicates or collaborates with infrastructure components (e.g., operation system functions, database capability, telecommunication functions). Although this type of coupling is necessary, it should be limited to a small number of components or classes within a system. Software must communicate internally and externally. Therefore, coupling is a fact of life. However, the designer should work to reduce coupling whenever possible and understand the ramifications of high coupling when it cannot be avoided.
There are many reasons why this could occur, Just a few:
Changes or clarification of user requirements
Expansion of project scope
Budgetary constraints invalidating original assumptions
Testing demonstrating unacceptable query processing time
Can XML be used to for data storage?
Yes, XML can be used for data storage. XML store data in the form of nodes and sub-nodes.
What is the definition of database clustering?
Database is defines as a collection related records/data. When the data in the database is grouped based on some classification it is called database clustering.
It is possible to have more than one table in a relational database?
You have to have more than one table in a relational database. In a relational database tables are designed to be related to other tables, so there has to be a minimum of two tables. Quite often there are a lot more than two.
Joins refer to the combination of related records to form a relation . There are six types of joins in database . Types of joins are cross join, natural join , right join , left join ,Inner join, Outer join.
INNER JOIN
OUTER JOIN
LEFT JOIN
RIGHT JOIN
NATURAL JOIN
CROSS JOIN
In special cases a table can join to itself (SELF JOIN)
What group function can be used to perform a count that includes NULL values?
You can not group a NULL value natively. You can however transform the NULL into so other unique value; dynamically, without writing this value to the database; and group by this.
You would accomplish this by implementing a coalesce T-SQL expression
For example lets say the MiddleName field is NULL in many cases and you want to to group by these.. You might want to turn this NULL into say an * for purposes of giving a value that you can group by.
Now you can group by all MiddleName entries and also use a where clause to excluded those values <> * giving you a sub grouping of those records ONLY having null.
The SQL command would look something like this:
SELECT coalesce(MiddleName, '*')
FROM YourTableNameHere
WHERE MiddleName LIKE '*'
GROUP BY MiddleName
The coalesce returns the first NON NULL value in the chain(you can have more than two values).
In the above example you will get the MiddleName if there is one and an * if the database value is NULL.
This is a SELECT so there is NO update to the database.
How to find unused stored procedures in sql server 2005?
There is no way to view this information by way of SQL Server Management Studio.
You could write a stored procedure against the SYSObjects tables to gather the information. You can also obtain information regarding the create / last accessed|used date of many objects from the same resources.
What is a fan trap in database design?
A fan trap is where one too many relationships 'fan' out from a central entity, so the link between the two entities at the many end becomes unclear. For example, if we had a central entity of Branch (of an organization) and two entities fanning out from it: Staff and Department, we cannot clearly link Staff with Department.
How would you describe a relational database?
Most modern databases are relational, meaning that data are stored in tables, consisting of rows and columns, and that data in different tables are related by the meanings of certain common columns.
What are properties of database?
The interrelated data/records are stored in the database . Properties of database are that it maintains integrity of data, security of data, reduces problem in accessing the data.
Is it possible for the computer to generate values that are used as the primary key column?
Yes. Often times, an automatically generated key column will be a normal primary key using the auto_increment attribute.
