Interview Questions.

Q1. What Is A Schema? How Is It Useful In Sql Servers?

The Schema refers to the overall structure of the database with all associated records like customers, get admission to privileges, interplay information between the specific tables and many others. The CREATE SCHEMA is the command that may be used to create the schema within the SQL Server. This while done may be used to re deploy the identical database in some other gadget for demonstrative or take a look at purposes. This holds intact the underlying framework over which the database has been built.

Q2. How Will You Enforce Security Using Stored Procedures?

Don't provide consumer get right of entry to at once to tables inside the software. Instead grant the capability to get entry to the processes that get admission to the tables. When system performed it'll execute the privilege of approaches owner. Users can't access tables besides via the method.

Q3. Any Attempt To Navigate Programmatically To Disabled Form In A Call_form Stack Is Allowed?

False

Q4. Whar Is An Index? What Are The Types Of Indexes? How Many Clustered Indexes Can Be Created On A Table? I Create A Separate Index On Each Column Of A Table. What Are The Advantages And Disadvantages Of

Indexes in SQL Server are much like the indexes in books. They assist SQL Server retrieve the statistics faster.

Indexes are of two types. Clustered indexes and non-clustered indexes. When you craete a clustered index on a desk, all of the rows inside the desk are stored within the order of the clustered index key. So, there can be most effective one clustered index per desk. Non-clustered indexes have their own storage break away the table information storage. Non-clustered indexes are stored as B-tree structures (so do clustered indexes), with the leaf stage nodes having the index key and it is row locater. The row located could be the RID or the Clustered index key, depending up at the absence or presence of clustered index at the desk.

If you create an index on every column of a desk, it improves the question performance, as the query optimizer can pick out from all the present indexes to give you an efficient execution plan. At the identical t ime, statistics modification operations (inclusive of INSERT, UPDATE, DELETE) will become slow, as whenever information changes in the table, all of the indexes need to be updated. Another drawback is that, indexes want disk space, the greater indexes you have, extra disk space is used.

Q5. What Are Synonyms Used For?

Mask the actual call and proprietor of an item.

Provide public get right of entry to to an item

Provide area transparency for tables, views or application gadgets of a far flung database.

Simplify the SQL statements for database customers.

Q6. What Is A Snapshot ?

Snapshots are read-best copies of a grasp desk located on a faraway node that is periodically refreshed to reflect modifications made to the master desk.

Q7. What Is Relation Between The Window And Canvas Views?

Canvas perspectives are the back ground gadgets on that you location the interface gadgets (Text gadgets), test bins, radio companies etc.,) and boilerplate objects (packing containers, traces, pictures and many others.,) that operators have interaction with us they run your form . Each canvas views displayed in a window.

Q8. What Are The Datatypes Available In Pl/sq. ?

Some scalar statistics sorts consisting of NUMBER, VARCHAR2, DATE, CHAR, LONG, BOOLEAN. Some composite facts kinds including RECORD & TABLE.

Q9. What Is The Use Of Control File ?

When an instance of an ORACLE database is started out, its manage document is used to perceive the database and redo log files that have to be opened for database operation to continue. It is also used in database recuperation.

Q10. What Are Modal Windows?

Modal windows are usually used as dialogs, and feature restrained functionality compared to modelless home windows. On some structures for example operators can't resize, scroll or iconify a modal window.

Q11. What Are The Different Parameter Types?

Text Parameters

Data Parameters

Q12. With Which Function Of Summary Item Is The Compute At Options Required?

Percent of general features.

Q13. What Does Commit Do ?

COMMIT makes permanent modifications because of all SQL statements within the transaction. The modifications made by using the SQL statements of a transaction come to be seen to other person periods transactions that start handiest after transaction is dedicated.

Q14. Explain How To Create A Scrollable Cursor With The Scroll Option.

Using the SCROLL keyword whilst asserting a cursor permits fetching of rows in any sequence.

Example:

DECLARE employee_curs SCROLL CURSOR FOR SELECT * FROM employee;

The lively set of the cursor is saved may be accessed in any order with out the need of establishing and final the cursor. The Scroll cursors can be set for choose and function cursors however now not insert or replace statements.

Q15. What Are Statistics, Under What Circumstances They Go Out Of Date, How Do You Update Them?

Statistics determine the selectivity of the indexes. If an listed column has specific values then the selectivity of that index is extra, as opposed to an index with non-unique values. Query optimizer makes use of these indexes in determining whether or not to choose an index or now not while executing a question.

Some situations under that you must replace data:

If there's massive trade inside the key values within the index

If a large quantity of information in an indexed column has been added, modified, or eliminated (that is, if the distribution of key values has modified), or the table has been truncated the usage of the TRUNCATE TABLE announcement and then repopulated

Database is upgraded from a previous model

Look up SQL Server books on-line for the following commands: UPDATE STATISTICS, STATS_DATE, DBCC SHOW_STATISTICS, CREATE STATISTICS, DROP STATISTICS, sp_autostats, sp_createstats, sp_updatestats.

Q16. What Is Raid? How Does It Help Storage Of Databases?

The RAID stands for Redundant Array of Independent Disks. With its own RAID controllers, the RAID implements a fail-secure storage mechanism with its very own backup mechanisms. There are distinctive configurations of the RAID that each one supply us the ACID residences of storage along with other such centers. This sort of storage will make the SQL Server database to be failsafe and stable. This can on occasion mean that the backup mechanisms and other such reliability measures can be taken off from the SQL Server level of operations.

Q17. Do User Parameters Appear In The Data Modal Editor In 2.Five?

No.

Q18. What Is The Mechanism Provided By Oracle For Table Replication ?

Snapshots and SNAPSHOT LOGs.

Q19. How Can You Enable Automatic Archiving ?

Shut the database

Backup the database

Modify/Include LOG_ARCHIVE_START_TRUE in init.Ora record.

Start up the database.

Q20. Define Transaction ?

A Transaction is a logical unit of work that accommodates one or greater SQL statements done by using a unmarried user.

Q21. Where Are My Tempfiles, I Don't See Them In V$datafile Or Dba_data_file?

Tempfiles, in contrast to regular datafiles, aren't indexed in v$datafile or dba_data_files. Instead question v$tempfile or dba_temp_files:

  SELECT * FROM v$tempfile;  SELECT * FROM dba_temp_files;

Q22. What Is A Data Segment?

Data section are the bodily areas inside a database block wherein the records related to tables and clusters are stored.

Q23. Where Is A Procedure Return In An External Pl/sq. Library Executed At The Client Or At The Server?

At the client.

Q24. How Many Windows In A Form Can Have Console?

Only one window in a shape can display the console, and also you can't alternate the console challenge at runtime.

Q25. What Are The Triggers Associated With Image Items?

When-photograph-activated fires, while the operators double clicks on an photo object, whilst-photo-pressed fires, whilst an operator clicks or double clicks on an photograph object.

Q26. Why Is A Where Clause Faster Than A Group Filter Or A Format Trigger?

Because, in a where clause the situation is carried out throughout information retrieval then after retrieving the records.

Q27. What Is Read-simplest Transaction ?

A Read-Only transaction ensures that the results of every question performed within the transaction are steady with appreciate to the identical factor in time.

Q28. How Can A Cross Product Be Created?

By deciding on the move merchandise device and drawing a brand new institution surrounding the base institution of the go merchandise.

Q29. What Is Trigger Associated With The Timer?

When-timer-expired.

Q30. What Is Lexical Reference? How Can It Be Created?

Lexical reference is place_holder for textual content that can be embedded in a sq. Statements. A lexical reference can be created using & earlier than the column or parameter call.

Q31. What Are User Defined Datatypes And When You Should Go For Them?

User defined datatypes allow you to make bigger the bottom SQL Server datatypes by means of imparting a descriptive name, and format to the database. Take as an example, on your database, there's a column referred to as Flight_Num which appears in many tables. In a lot of these tables it ought to be varchar(8). In this situation you can create a consumer described datatype known as Flight_num_type of varchar(8) and use it across all your tables.

Q32. What Is An Integrity Constrains ?

An integrity constraint is a declarative way to define a business rule for a column of a table.

Q33. How Do You Create A New Session While Open A New Form?

Using open_form integrated placing the session alternative Ex. Open_form('Stocks ',lively,session). Whilst invoke the mulitiple paperwork with open shape and call_form inside the same application, country whether the subsequent are proper/False

Q34. What Is System Tablespace And When Is It Created?

Every Oracle database carries a tablespace named SYSTEM, that is routinely created when the database is created. The SYSTEM tablespace continually includes the statistics dictionary tables for the complete database.

Q35. Is It Possible To Link Two Groups Inside A Cross Products After The Cross Products Group Has Been Created?

No.

Q36. What Is A Display Item?

Display items are just like textual content gadgets but save most effective fetched or assigned values. Operators can't navigate to a show object or edit the fee it consists of.

Q37. What Is Use Of Term?

The term document which key's correspond to which oracle report functions.

Q38. What Are The Options Available To Refresh Snapshots ?

COMPLETE - Tables are completely regenerated the usage of the snapshots question and the master tables on every occasion the image referenced.

FAST - If simple picture used then a image log can be used to send the changes to the picture tables.

FORCE - Default fee. If viable it plays a FAST refresh; Otherwise it'll perform a complete refresh.

Q39. What's The Difference Between A Primary Key And A Unique Key?

Both number one key and specific put into effect uniqueness of the column on which they're defined. But by using default number one key creates a clustered index on the column, in which are specific creates a nonclustered index by using default. Another most important difference is that, number one key would not allow NULLs, however unique key permits one NULL simplest.

Q40. What Is The Advantage Of The Library?

Libraries provide a handy means of storing patron-side program devices and sharing them amongst a couple of programs. Once you create a library, you could attach it to another shape, menu, or library modules. When you can call library software devices from triggers menu objects instructions and person named routine, you write within the modules to which you have connect the library. When a library attaches any other library, software gadgets within the first library can reference program gadgets inside the attached library. Library support dynamic loading-that is library software gadgets are loaded into an utility simplest while wanted. This can substantially lessen the run-time reminiscence requirements of programs.

Q41. How Can You Know That Statistics Should Be Updated?

Statistics represent the individuality for the indexes which are getting used for choosing the facts. This could make the question execution quite green. The tables that we're coping with if truncated and repopulated, there is a superb danger that the indexes and information are out of sync and that is whilst we ought to update the statistics. There are also other situations like when the desk has been changed and lot of rows had been introduced currently or like when a server has been updated with distinct version of software. These additionally give us the reason to use the UPDATE_STATISTICS, DBCC SHOW_STATISTICS and so on to update it hence.

Q42. What Is Overloading Of Procedures ?

The Same system call is repeated with parameters of various datatypes and parameters in exceptional positions, various range of parameters is called overloading of processes. E.G. DBMS_OUTPUT put_line

Q43. How Can You Enforce Referential Integrity In Snapshots ?

Time the references to occur while grasp tables aren't in use. Peform the reference manually straight away locking the master tables. We can be a part of tables in snapshots by using growing a complicated snapshots on the way to be primarily based at the master tables.

Q44. What Is A View ?

A view is a digital table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

Q45. Explain About Stacked Canvas Views?

Stacked canvas view is displayed in a window on pinnacle of, or "stacked" at the content canvas view assigned to that identical window. Stacked canvas perspectives obscure some part of the underlying content material canvas view, and or often shown and hidden programmatically.

Q46. What Is Sql*loader And What Is It Used For?

SQL*Loader is a bulk loader application used for moving information from outside documents into the Oracle database. Its syntax is similar to that of the DB2 Load application, but comes with extra options.

SQL*Loader helps diverse load codecs, selective loading, and multi-desk masses.

Q47. What Is Bind Reference And How Can It Be Created?

Bind reference are used to update the single fee in square, pl/sq. Statements a bind reference may be created the use of a (:) earlier than a column or a parameter call.

Q48. What Is Forms_ddl?

Issues dynamic Sql statements at run time, together with server aspect pl/SQl and DDL

Q49. What Are The Three Types Of User Exits Available ?

Oracle Precompiler exits, Oracle call interface, NonOracle user exits.

Q50. Explain Different Isolation Levels?

An isolation degree determines the diploma of isolation of information between concurrent transactions. The default SQL Server isolation level is Read Committed. Here are the other isolation tiers (within the ascending order of isolation): Read Uncommitted, Read Committed, Repeatable Read, Serializable. See SQL Server books online for an explanation of the isolation degrees. Be positive to study approximately SET TRANSACTION ISOLATION LEVEL, which helps you to customise the isolation degree at the connection level.

CREATE INDEX myIndex ON myTable(myColumn)