What is hybrid slowly changing dimension? 2008-03-16 07:07:31 Hybrid SCDs are combination of both SCD 1 and SCD 2. It may happenthat in a table, some columns are important and we need to trackchanges for them i.e capture the historical data for them whereas insome columns even if the data changes, we don't care.
What are slowly changing dimensions (SCD)? 2008-03-16 07:07:09 SCD is abbreviation of Slowly changing dimensions. SCD applies tocases where the attribute for a record varies over time. There arethree different types of SCD.1) SCD1 : The new record replaces the original record. Only onerecord exist in database - current data.2) SCD2 : A new record is added into the customer dimension table.Two records exist in database - current data and previous history data.3) SCD3 : The original data is modified to include new data. Onerecord exist in database - new information are attached with oldinformation in same row.
What is factless facts table? 2008-03-16 07:06:50 A fact table which does not contain numeric fact columns it is calledfactless facts
table.
What are non-additive facts? 2008-03-16 07:06:28 Non-additive facts
are facts that cannot be summed up for any of thedimensions present in the fact table. However they are not consideredas useless. If there is changes in dimensions the same facts can beuseful.
What is a level of Granularity of a fact table? 2008-03-16 07:06:09 Level of granularity means level
of detail that you put into the fact table in a data warehouse. Level of granularity would mean what detailare you willing to put for each transactional fact.
How do you load the time dimension? 2008-03-16 07:05:38 Time dimensions are usually loaded by a program that loops throughall possible dates that may appear in the data. 100 years may berepresented in a time dimension, with one row per day.
What is conformed fact? 2008-03-16 07:05:17 Conformed dimensions are the dimensions which can be used acrossmultiple Data Marts in combination with multiple facts tablesaccordingly.
What are conformed dimensions? 2008-03-16 07:04:55 Conformed dimensions mean the exact same thing with every possiblefact table to which they are joined. They are common to the cubes.
What is real time data-warehousing? 2008-03-16 07:04:28 Data warehousing captures business activity data. Real-time datawarehousing captures business activity data as it occurs. As soon asthe business activity is complete and there is data about it, thecompleted activity data flows into the data warehouse and becomesavailable instantly. Read more:real time
What are the different index configurations a table can have? 2008-03-29 10:48:51 A table can have one of the following index configurations:No indexesA clustered indexA clustered index and many nonclustered indexesA nonclustered indexMany nonclustered indexes Read more:different
What is the difference between clustered and a non-clustered index? 2008-03-29 10:48:33 A clustered index is a special type of index that reorders the way records in the table are physicallystored. Therefore table can have only one clustered index. The leaf nodes of a clustered index containthe data pages.A nonclustered index is a special type of index in which the logical order of the index does not matchthe physical stored order of the rows on disk. The leaf node of a nonclustered index does not consist ofthe data pages. Instead, the leaf nodes contain index rows. Read more:difference
What is Index? 2008-03-29 10:47:51 An index is a physical structure containing pointers to the data. Indices are created in an existing tableto locate rows more quickly and efficiently. It is possible to create an index on one or more columns ofa table, and each index is given a name. The users cannot see the indexes, they are just used to speedup queries. Effective indexes are one of the best ways to improve performance in a databaseapplication. A table scan happens when there is no index available to help a query. In a table scan SQLServer examines every row in the table to satisfy the query results. Table scans are sometimesunavoidable, but on large tables, scans have a terrific impact on performance.Clustered indexes define the physical sorting of a database table’s rows in the storage media. For thisreason, each data Read more:Index
What is View? 2008-03-29 10:47:06 A simple view can be thought of as a subset of a table. It can be used for retrieving data, as well asupdating or deleting rows. Rows updated or deleted in the view are updated or deleted in the table theview was created with. It should also be noted that as data in the original table changes, so does datain the view, as views are the way to look at part of the original table. The results of using a view arenot permanently stored in the database. The data accessed through a view is actually constructed usingstandard T-SQL select command and can come from one to many different base tables or even otherviews.
What is Trigger? 2008-03-29 10:46:39 A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE)occurs. Triggers are stored in and managed by the DBMS.Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion. A trigger cannot be called or executed;the DBMS automatically fires the trigger as a result of a data modification to the associated table.Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that isstored at the database level. Stored procedures, however, are not event-drive and are not attached to aspecific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to theprocedure while triggers are implicitly executed. In addition, triggers can also execute storedpr
What is Stored Procedure? 2008-03-29 10:45:46 A stored procedure is a named group of SQL statements that have been previously created and storedin the server database. Stored procedures accept input parameters so that a single procedure can beused over the network by several clients using different input data. And when the procedure ismodified, all clients automatically get the new version. Stored procedures reduce network traffic andimprove performance. Stored procedures can be used to help ensure the integrity of the database.e.g. sp_helpdb, sp_renamedb, sp_depends etc. Read more:Procedure
What are different normalization forms? 2008-03-29 10:45:06 1NF: Eliminate Repeating GroupsMake a separate table for each set of related attributes, and give each table a primary key. Each fieldcontains at most one value from its attribute domain.2NF: Eliminate Redundant DataIf an attribute depends on only part of a multi-valued key, remove it to a separate table.3NF: Eliminate Columns Not Dependent On KeyIf attributes do not contribute to a description of the key, remove them to a separate table. Allattributes must be directly dependent on the primary keyBCNF: Boyce-Codd Normal FormIf there are non-trivial dependencies between candidate key attributes, separate them out into distincttables.4NF: Isolate Independent Multiple RelationshipsNo table may contain two or more 1:n or n:m relationships that are not directly related.5NF: Isolate Semantically Read more:different
What is normalization? 2008-03-29 10:43:52 Database normalization is a data design and organization process applied to data structures based onrules that help build relational databases. In relational database design, the process of organizing datato minimize redundancy. Normalization usually involves dividing a database into two or more tables anddefining relationships between the tables. The objective is to isolate data so that additions, deletions,and modifications of a field can be made in just one table and then propagated through the rest of thedatabase via the defined relationships.
What is RDBMS? 2008-03-29 10:42:34 Relational Data Base Management Systems (RDBMS) are database management systems that maintaindata records and indices in tables. Relationships may be created and maintained across and among thedata and tables. In a relational database, relationships between data items are expressed by means oftables. Interdependencies among these tables are expressed by data values rather than by pointers.This allows a high degree of data independence. An RDBMS has the capability to recombine the dataitems from different files, providing powerful tools for data usage.
What is @@ERROR? 2008-04-04 11:27:18 The @@ERROR automatic variable returns the error code of the last Transact-SQL statement. If therewas no error, @@ERROR returns zero. Because @@ERROR is reset after each Transact-SQL statement,it must be saved to a variable if it is needed to process it further after checking it.
Can a stored procedure call itself or recursive stored procedure? How many level SP nesting 2008-04-04 11:26:50 Can a stored
procedure call itself or recursive stored procedure? How many level
SP nestingpossible?Ans:Yes. Because Transact-SQL supports recursion, you can write stored procedures that call themselves.Recursion can be defined as a method of problem solving wherein the solution is arrived at byrepetitively applying it to subsets of the problem. A common application of recursive logic is to performnumeric computations that lend themselves to repetitive evaluation by the same processing steps.Stored procedures are nested when one stored procedure calls another or executes managed code byreferencing a CLR routine, type, or aggregate. You can nest stored procedures and managed codereferences up to 32 levels.
What is SQL server agent? 2008-04-04 11:26:23 SQL Server agent plays an important role in the day-to-day tasks of a database administrator (DBA). Itis often overlooked as one of the main tools for SQL Server management. Its purpose is to ease theimplementation of tasks for the DBA, with its full-function scheduling engine, which allows you toschedule your own jobs and scripts. Read more:SQL
, server
What are the authentication modes in SQL Server? How can it be changed? 2008-04-04 11:24:51 Windows mode and mixed mode (SQL
& Windows).To change authentication mode in SQL Server
click Start, Programs, Microsoft SQL Server and click SQLEnterprise Manager to run SQL Enterprise Manager from the Microsoft SQL Server program group.Select the server then from the Tools menu select SQL Server Configuration Properties, and choose theSecurity page.
What kind of User-Defined Functions can be created? 2008-04-04 11:23:34 There are three types of User-Defined functions in SQL Server 2000 and they are Scalar, Inline Table-Valued and Multi-statement Table-valued.Scalar User-Defined FunctionA Scalar user-defined function returns one of the scalar data types. Text, ntext, image and timestampdata types are not supported. These are the type of user-defined functions that most developers areused to in other programming languages. You pass in 0 to many parameters and you get a returnvalue.Inline Table-Value User-Defined FunctionAn Inline Table-Value user-defined function returns a table data type and is an exceptional alternativeto a view as the user-defined function can pass parameters into a T-SQL select command and inessence provide us with a parameterized, non-updateable view of the underlying tables.Multi-stat Read more:Functions
What is User Defined Functions? 2008-04-04 11:21:34 User-Defined Functions
allow to define its own T-SQL functions that can accept 0 or more parametersand return a single scalar data value or a table data type.
What is SQL Profiler? 2008-04-04 11:21:14 SQL Profiler is a graphical tool that allows system administrators to monitor events in an instance ofMicrosoft SQL Server. You can capture and save data about each event to a file or SQL Server table toanalyze later. For example, you can monitor a production environment to see which stored proceduresare hampering performance by executing too slowly.Use SQL Profiler to monitor only the events in which you are interested. If traces are becoming toolarge, you can filter them based on the information you want, so that only a subset of the event data iscollected. Monitoring too many events adds overhead to the server and the monitoring process and cancause the trace file or trace table to grow very large, especially when the monitoring process takesplace over a long period of time. Read more:SQL
What are types of sub-queries? 2008-04-04 11:20:53 Single-row subquery, where the subquery returns only one row.Multiple-row subquery, where the subquery returns multiple rows,.andMultiple column subquery, where the subquery returns multiple columns. Read more:types
What is sub-query? Explain properties of sub-query. 2008-04-04 11:20:27 Sub-queries are often referred to as sub-selects, as they allow a SELECT statement to be executedarbitrarily within the body of another SQL statement. A sub-query is executed by enclosing it in a set ofparentheses. Sub-queries are generally used to return a single row as an atomic value, though theymay be used to compare values against multiple rows with the IN keyword.A subquery is a SELECT statement that is nested within another T-SQL statement. A subquery SELECTstatement if executed independently of the T-SQL statement, in which it is nested, will return a resultset. Meaning a subquery SELECT statement can standalone and is not depended on the statement inwhich it is nested. A subquery SELECT statement can return any number of values, and can be foundin, the column list of a SELECT stat
Recommend Site To A Friend
