Wednesday, June 30, 2010
This is regarded as one of the most successful open source database in the world. This is also used to create advanced applications. This relies on Object relational database management system. Familiarity with UNIX and Linux can be an added advantage while using PostgreSQL.
2) State some of the advanced features of PostgreSQL?
These are the following features which are present in PostgreSQL they are
1) Object relational database
2) Extensibility and support for SQL
3) Database validation and flexible API
4) Procedural languages and MVCC
5) Client server and WAL.
3) Explain about Write Ahead logging?
This feature increases the reliability of the database by logging changes before any changes or updations to the data base. This provides log of database incase of a database crash. This helps to start the work from the point it was discontinued.
4) Explain about Multi version concurrency control?
Multi version concurrency control or MVCC is used to avoid unnecessary locking of the database. This removes the time lag for the user to log into his database. This feature or time lag occurs when some one else is on the content. All the transactions are kept as a record.
5) What are the languages which PostgreSQL supports?
Some of the languages which PostgreSQL supports are as follows: -
It supports a language of its own known as PL/pgSQL and it supports internal procedural languages. Pl/pgSQL can be compared to oracle, PL/SQL, etc. Languages such as Perl, Python, TCL can be used as embedded languages.
6) Explain about the command enable debug?
This command is used for enabling compilation of all libraries and applications. This process generally slows down the system and it also increases the binary file size. Debugging symbols are present which can assist developers in noticing bugs and problems associated with their script.
7) Explain about functions in PostgreSQL?
Functions are important because they help the code to be executed on the server. Some of the languages which can program functions for efficient use are PL/pgSQL which is the native language of PostgreSQL. Scripting languages are supported by many languages such as PHP, Perl, Python, etc. PL/R a statistical language can also be used.
8) Explain about indices of PostgreSQL?
There are built in functions such as B-tree, hash table, and GIST indices can be used or users can define their own indices. PostgreSQL can scan the index backwards. Expression index could be created with the result of an expression. Partial index created with addition of WHERE clause.
9) Explain about Triggers?
By SQL query you can trigger an event. Triggers can be activated with the help of INSERT and UPDATE queries. These can be attached to tables. Triggers more than one can be triggered alphabetically. These triggers have the capability to invoke functions from other languages.
10) What are the different data types supported by PostgreSQL?
There are different data types which are supported they are: -
1) Arbitrary precision numeric’s
2) Geometric primitives
4) XML etc
Users can create their own indexes and make them indexed.
11) Explain about database administration tools?
There are various data administration tools they are
Most of these tools are front end administration tools and web based interfaces. Out of these phppgadmin is the most popular one.
12) Explain about pgadmin?
Pgadmin forms a graphical front end administration tool. This feature is available under free software released under Artistic License. Pgadmin iii is the new database administration tool released under artistic license.
13) How do you create a data base with postgreSQL?
Creating a database is the primary step in creating a database. A command
This creates a new database and a message displays CREATE DATABASE which indicates that the creation of the database was successful.
14) What are the various enhancements to the straight relational data model by PostgreSQL?
There are various enhancements provided to the straight relational data model by postgre SQl they are support for arrays which includes multiple values, inheritance, functions and extensibility. Jargon differs because of its object oriented nature where tables are called as classes.
15) Explain about tokens?
Tokens are also known to contain several special character symbols. It can be considered as keyword, constant, identifier and quoted identifier. Keywords include pre defined SQL meanings and SQL commands. Variable names such as tables, columns, etc are represented by identifiers.
16) Explain about string constants?
String constant contains a sequence of characters bound by single quotes. This feature is used during insertion of a character or passing character to database objects. PostgreSQL allows the usage of single quotes but embedded by a C style backslash. This feature is important in parsing data.
17) Explain about concurreny with the help of MVCC?
Multi version concurrency control is used to manage concurrency. This feature is very useful because changes made in the database will not be visible to other users until the transaction is completed. This removes the need for read locks. ACID principles are given a further boost by this feature and can be implemented in general.
Tuesday, June 29, 2010
Oracle database is comprised of three types of files. One or more datafiles, two are more redo log files, and one or more control files.
What are the components of logical database structure of Oracle database?
There are tablespaces and database's schema objects.
What is a tablespace?
A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.
What is SYSTEM tablespace and when is it created?
Every Oracle database contains a tablespace named SYSTEM, which is automatically created when the database is created. The SYSTEM tablespace always contains the data dictionary tables for the entire database.
Explain the relationship among database, tablespace and data file ?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.
What is schema?
A schema is collection of database objects of a user.
What are Schema Objects?
Schema objects are the logical structures that directly refer to the database's data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.
Can objects of the same schema reside in different tablespaces?
Can a tablespace hold objects from different schemes?
What is Oracle table?
A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
What is an Oracle view?
A view is a virtual 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.)
What is Partial Backup ?
A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
What is Mirrored on-line Redo Log ?
A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.
What is Full Backup ?
A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.
Can a View based on another View ?
Can a Tablespace hold objects from different Schemes ?
Can objects of the same Schema reside in different tablespace ?
What is the use of Control File ?
When an instance of an ORACLE database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. It is also used in database recovery.
Do View contain Data ?
Views do not contain or store data.
What are the Referential actions supported by FOREIGN KEY integrity constraint ?
UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data. DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted.
What are the type of Synonyms?
There are two types of Synonyms Private and Public.
What is a Redo Log ?
The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.
What is an Index Segment ?
Each Index has an Index segment that stores all of its data.
Explain the relationship among Database, Tablespace and Data file?
Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace
What are the different type of Segments ?
Data Segment, Index Segment, Rollback Segment and Temporary Segment.
What are Clusters ?
Clusters are groups of one or more tables physically stores together to share common columns and are often used together.
What is an Integrity Constrains ?
An integrity constraint is a declarative way to define a business rule for a column of a table.
What is an Index ?
An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
What is an Extent ?
An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.
What is a View ?
A view is a virtual 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.)
What is Table ?
A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns
Can a view based on another view?
What are the advantages of views?
- Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
- Hide data complexity.
- Simplify commands for the user.
- Present the data in a different perspective from that of the base table.
- Store complex queries.
What is an Oracle sequence?
A sequence generates a serial list of unique numbers for numerical columns of a database's tables.
What is a synonym?
A synonym is an alias for a table, view, sequence or program unit.
What are the types of synonyms?
There are two types of synonyms private and public.
What is a private synonym?
Only its owner can access a private synonym.
What is a public synonym?
Any database user can access a public synonym.
What are synonyms used for?
- Mask the real name and owner of an object.
- Provide public access to an object
- Provide location transparency for tables, views or program units of a remote database.
- Simplify the SQL statements for database users.
What is an Oracle index?
An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
How are the index updates?
Indexes are automatically maintained and used by Oracle. Changes to table data are automatically incorporated into all relevant indexes.
What is a Tablespace?
A database is divided into Logical Storage Unit called tablespace. A tablespace is used to grouped related logical structures together
What is Rollback Segment ?
A Database contains one or more Rollback Segments to temporarily store "undo" information.
What are the Characteristics of Data Files ?
A data file can be associated with only one database. Once created a data file can't change size. One or more data files form a logical unit of database storage called a tablespace.
How to define Data Block size ?
A data block size is specified for each ORACLE database when the database is created. A database users and allocated free database space in ORACLE data blocks. Block size is specified in INIT.ORA file and can’t be changed latter.
What does a Control file Contain ?
A Control file records the physical structure of the database. It contains the following information.
Names and locations of a database's files and redolog files.
Time stamp of database creation.
What is difference between UNIQUE constraint and PRIMARY KEY constraint ?
A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls.
What is Index Cluster ?
A Cluster with an index on the Cluster Key
When does a Transaction end ?
When it is committed or Rollbacked.
What is the effect of setting the value "ALL_ROWS" for OPTIMIZER_GOAL parameter of the ALTER SESSION command ? What are the factors that affect OPTIMIZER in choosing an Optimization approach ?
Answer The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement.
What is the effect of setting the value "CHOOSE" for OPTIMIZER_GOAL, parameter of the ALTER SESSION Command ?
The Optimizer chooses Cost_based approach and optimizes with the goal of best throughput if statistics for atleast one of the tables accessed by the SQL statement exist in the data dictionary. Otherwise the OPTIMIZER chooses RULE_based approach.
How does one create a new database? (for DBA)
One can create and modify Oracle databases using the Oracle "dbca" (Database Configuration Assistant) utility. The dbca utility is located in the $ORACLE_HOME/bin directory. The Oracle Universal Installer (oui) normally starts it after installing the database server software.
One can also create databases manually using scripts. This option, however, is falling out of fashion, as it is quite involved and error prone. Look at this example for creating and Oracle 9i database:
CONNECT SYS AS SYSDBA
ALTER SYSTEM SET DB_CREATE_FILE_DEST='/u01/oradata/';
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_1='/u02/oradata/';
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_2='/u03/oradata/';
What database block size should I use? (for DBA)
Oracle recommends that your database block size match, or be multiples of your operating system block size. One can use smaller block sizes, but the performance cost is significant. Your choice should depend on the type of application you are running. If you have many small transactions as with OLTP, use a smaller block size. With fewer but larger transactions, as with a DSS application, use a larger block size. If you are using a volume manager, consider your "operating system block size" to be 8K. This is because volume manager products use 8K blocks (and this is not configurable).
What are the different approaches used by Optimizer in choosing an execution plan ?
Rule-based and Cost-based.
What does ROLLBACK do ?
ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.
How does one coalesce free space ? (for DBA)
SMON coalesces free space (extents) into larger, contiguous extents every 2 hours and even then, only for a short period of time.
SMON will not coalesce free space if a tablespace's default storage parameter "pctincrease" is set to 0. With Oracle 7.3 one can manually coalesce a tablespace using the ALTER TABLESPACE ... COALESCE; command, until then use:
SQL> alter session set events 'immediate trace name coalesce level n';
Where 'n' is the tablespace number you get from SELECT TS#, NAME FROM SYS.TS$;
You can get status information about this process by selecting from the SYS.DBA_FREE_SPACE_COALESCED dictionary view.
How does one prevent tablespace fragmentation? (for DBA)
Always set PCTINCREASE to 0 or 100.
Bizarre values for PCTINCREASE will contribute to fragmentation. For example if you set PCTINCREASE to 1 you will see that your extents are going to have weird and wacky sizes: 100K, 100K, 101K, 102K, etc. Such extents of bizarre size are rarely re-used in their entirety. PCTINCREASE of 0 or 100 gives you nice round extent sizes that can easily be reused. E.g.. 100K, 100K, 200K, 400K, etc.
Use the same extent size for all the segments in a given tablespace. Locally Managed tablespaces (available from 8i onwards) with uniform extent sizes virtually eliminates any tablespace fragmentation. Note that the number of extents per segment does not cause any performance issue anymore, unless they run into thousands and thousands where additional I/O may be required to fetch the additional blocks where extent maps of the segment are stored.
Where can one find the high water mark for a table? (for DBA)
There is no single system table, which contains the high water mark (HWM) for a table. A table's HWM can be calculated using the results from the following SQL statements:
WHERE OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);
ANALYZE TABLE owner.table ESTIMATE STATISTICS;
WHERE OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);
Thus, the tables' HWM = (query result 1) - (query result 2) - 1
NOTE: You can also use the DBMS_SPACE package and calculate the HWM = TOTAL_BLOCKS - UNUSED_BLOCKS - 1.
What is COST-based approach to optimization ?
Considering available access paths and determining the most efficient execution plan based on statistics in the data dictionary for the tables accessed by the statement and their associated clusters and indexes.
What does COMMIT do ?
COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.
How are extents allocated to a segment? (for DBA)
Oracle8 and above rounds off extents to a multiple of 5 blocks when more than 5 blocks are requested. If one requests 16K or 2 blocks (assuming a 8K block size), Oracle doesn't round it up to 5 blocks, but it allocates 2 blocks or 16K as requested. If one asks for 8 blocks, Oracle will round it up to 10 blocks.
Space allocation also depends upon the size of contiguous free space available. If one asks for 8 blocks and Oracle finds a contiguous free space that is exactly 8 blocks, it would give it you. If it were 9 blocks, Oracle would also give it to you. Clearly Oracle doesn't always round extents to a multiple of 5 blocks.
The exception to this rule is locally managed tablespaces. If a tablespace is created with local extent management and the extent size is 64K, then Oracle allocates 64K or 8 blocks assuming 8K-block size. Oracle doesn't round it up to the multiple of 5 when a tablespace is locally managed.
Can one rename a database user (schema)? (for DBA)
No, this is listed as Enhancement Request 158508. Workaround:
Do a user-level export of user A
create new user B
Import system/manager fromuser=A touser=B
Drop user A
Thursday, June 24, 2010
Ecstasoft Solutions (TN) Pvt Ltd (www.ecstasoft.com)
- Exclusive Job for Chetanaites…
Ecstasoft Solutions (TN) Pvt Ltd is a rapidly growing software development company specialized in Web Applications, Custom Software solutions, Website designing and E-commerce solutions. We are located in Coimbatore (India) providing Offshore Development services to the clients in US, UK, Australia, and Singapore.
The Benefits with our Company is to utilize the New technologies, Compete with the Fortune companies standard, Accelerate Cost effective solutions, Rapid Implementation, Flexibility, Achieving the Quality standard to the international level.
We would like you to publish below job requirement in your walkinfeed.com
Freshers : PHP Developers @ Coimbatore
* This is NOT a direct Walk-In. You need to apply through ChetanaS as mentioned below & Only Shortlisted candidates will be called for personal interview.
Job Position: PHP Developer
Job Category: IT / Software
Job Location: Coimbatore, Tamilnadu
* Important: Please apply only if you are interested to work at Coimbatore.
Desired Experience: 0 Years
* Important: Freshers can apply only if they have below mentioned technical skills.
Mandatory Skills: PHP, MYSQL, HTML
• Should have Basic Skills in PHP, MYSQL, HTML
• Should be good in communication.
• CMS Knowledge Preferred.
• Junior PHP Developers.
How to Apply for this Job ?
* This is NOT a direct Walk-In. You need to apply at given Email Id & Only Shortlisted candidates will be called for personal interview.
* Please apply ONLY IF you have above mentioned skills. Clearly mention the same in your resume. Otherwise, your resume will NOT be considered.
If eligible, Please send your resume at : firstname.lastname@example.org
Job Code: CHETANAS
Please mention the Subject Line of your Email in the below format:
– – – – –
CHETANAS – PHP Developer – Coimbatore – PHP, MYSQL, HTML – B.Tech (CSE) – Fresher
* You must apply exactly in the above mentioned format only. Otherwise, resumes will NOT be considered.
Thanks & Regards,
Monday, June 21, 2010
MphasiS an HP Company is recruiting B.E./B.Tech/MCA/BCA/B.Sc candidates who graduated in 2009 for fresher positions.
To register yourself please visit: http://mphasis.aspiringminds.in./
To learn about Hiring Process, Profile and compensation please visit:
* If offered a job, will be required to undergo a 3 month training in the MphasiS Learning Academy in Mangalore where the candidate will be paid a stipend of INR 10000 per month.
* Only after successfully completing training, will be made a permanent offer.
* For BE/B.Tech/MCA candidates the salary upon passing the training program will be INR 200000 per annum and will be eligible for a bonus of INR 50000 upon completion of 2 yrs.
* For BCA/B.Sc Candidates salary upon passing the training program will be INR 180000 per annum.
* Candidates can be placed in any of the MphasiS offices across India based on the project.
* Salary and benefits will be the same as mentioned above regardless of location.
Job Title : Associate Software Engineer
About Company :
Robert Bosch Engineering and Business Solutions Limited (RBEI) is a 100% owned subsidiary of Robert Bosch GmbH.
We provide engineering, IT and business services for the automotive, industrial, consumer goods and building technonlogy divisions of the Bosch group worldwide. We offer services – such as ECU development, Process Consulting, Mechanical and Electronic Engineering, VLSI Services, Shared Services in Accounting and Business Processes, Translation / Documentation and E-Learning.
Experience: Freshers who have passed out in 2009 with over 70% aggregate only need to apply.
Job Location: Bengaluru/Bangalore, Coimbatore
Education: B.Tech/B.E. – Electrical, Electronics/Telecomunication, Instrumentation
Job Description :
Embedded software development in C, Assembly
Work covers any or all phases of software project lifecycle in the Automotive Domain
Good analytical and communication skills, and innovative problem solving skills are necessary.
For more details visit: http://www.boschindia.com
All the Best!!!!!!
Monday, June 14, 2010
Impiger Technologies ( www.impigertech.com) is in the process of recruiting freshers for its development Centre at Coimbatore.
We would request that the students from your college - 2010 pass outs-, BE CS, BTech IT, MCA, may pl be informed of the requirements and the resumes may pl be sent to us asap.
The tests and interviews would be held at our office at IInd Floor, Diamond Complex, 731 TRICHY ROAD, Ramanathapuram, Coimbatore -45 and the office Tel No is 3928300.
During training period they would be paid a consolidated salary of Rs 10000 per month. Training period is approx 3 months after which they would be placed as Software Engineers with CTC 1.8 -2.7.
The students would have to take a technical Level test ( Logic and C C++ OR JAVA) and then a level II test on Programming. It would be good if the students can brush up the fundamentals before they take the test .
The final round will be an interview.
I look forward to getting the candidates from your college.
Pl confirm receipt of this mail.
Impiger Technologies (P) Ltd
--------All The Best-----
Thursday, June 10, 2010
1. Skilled Java Professionals with minimum 2 years of work experience.
Skill Set & Experience Needed:
A full time degree in B.E./ B.Tech/ MCA/ M.E./ M.Tech/ M.Sc (SE) with 70% aggregate
Should have minimum experience of 2 years in the design and development of Java applications.
Strong in Core Java Concepts and SQL
Sound understanding in Object Oriented and Design concepts
Experience to develop applications with Eclipse RCP
Excellent communication skills and customer handling skills is a must
Strong debugging and problem solving skills
Should be proactive and energetic to stretch extra hours to deliver under pressure and in compressed timelines
Position: Senior Software Engineer
Job Location: Coimbatore, India
Where to apply: email@example.com
Salary is not a constraint for the right candidate
2. Experienced System side professionals with 2-6 years of experienced
Skill Set Requirements
The candidate should possess between 2 and 6 years of experience with proven track record in his/her technical expertise
Excellent knowledge in System Security, Virtualization, Linux/Unix OS and Networking
Hands-on experience in Programming, Shell Scripting and Infrastructure Solutions.
Product / Solution architecture skills will be an added advantage
Should be passionate, dynamic with vibrant energy to motivate people
Should be extremely flexible in handling different assignments and working in different time zones
Should be willing to travel for short-term assignments, if required
Should be versatile and adoptable to demanding business environments
Should be a thoughtful and crisp communicator
Will be responsible to interpret a set of business requirements into tactical technical tasks
Will be responsible to manage a team of around 4 to 8 resources comprising of engineers and senior engineers
Will be entirely responsible for scheduling, project management and deliverables
Will be responsible to take initiative and make recommendations for business process improvement
Will be responsible to groom and mentor his/her team engineers
Will be involved in contract negotiations as and when required
Position: Tech Lead
Job Location: Coimbatore, India
Where to apply: firstname.lastname@example.org
ViSolve Recruitment Team
Tel: +91-422- 231-4200 +91-422- 231-5200
2. How do you start MySQL on Linux? - /etc/init.d/mysql start
3. Explain the difference between mysql and mysqli interfaces in PHP? - mysqli is the object-oriented version of mysql library functions.
4. What’s the default port for MySQL Server? - 3306
5. What does tee command do in MySQL? - tee followed by a filename turns on MySQL logging to a specified file. It can be stopped by command notee.
6. Can you save your connection settings to a conf file? - Yes, and name it ~/.my.conf. You might want to change the permissions on the file to 600, so that it’s not readable by others.
7. How do you change a password for an existing user via mysqladmin? - mysqladmin -u root -p password "newpassword"
8. Use mysqldump to create a copy of the database? - mysqldump -h mysqlhost -u username -p mydatabasename > dbdump.sql
9. Have you ever used MySQL Administrator and MySQL Query Browser? Describe the tasks you accomplished with these tools.
10. What are some good ideas regarding user security in MySQL? - There is no user without a password. There is no user without a user name. There is no user whose Host column contains % (which here indicates that the user can log in from anywhere in the network or the Internet). There are as few users as possible (in the ideal case only root) who have unrestricted access.
11. Explain the difference between MyISAM Static and MyISAM Dynamic. - In MyISAM static all the fields have fixed width. The Dynamic MyISAM table would include fields such as TEXT, BLOB, etc. to accommodate the data types with various lengths. MyISAM Static would be easier to restore in case of corruption, since even though you might lose some data, you know exactly where to look for the beginning of the next record.
12. What does myisamchk do? - It compressed the MyISAM tables, which reduces their disk usage.
13. Explain advantages of InnoDB over MyISAM? - Row-level locking, transactions, foreign key constraints and crash recovery.
14. Explain advantages of MyISAM over InnoDB? - Much more conservative approach to disk space management - each MyISAM table is stored in a separate file, which could be compressed then with myisamchk if needed. With InnoDB the tables are stored in tablespace, and not much further optimization is possible. All data except for TEXT and BLOB can occupy 8,000 bytes at most. No full text indexing is available for InnoDB. TRhe COUNT(*)s execute slower than in MyISAM due to tablespace complexity.
15. What are HEAP tables in MySQL? - HEAP tables are in-memory. They are usually used for high-speed temporary storage. No TEXT or BLOB fields are allowed within HEAP tables. You can only use the comparison operators = and <=>. HEAP tables do not support AUTO_INCREMENT. Indexes must be NOT NULL.
16. How do you control the max size of a HEAP table? - MySQL config variable max_heap_table_size.
17. What are CSV tables? - Those are the special tables, data for which is saved into comma-separated values files. They cannot be indexed.
18. Explain federated tables. - Introduced in MySQL 5.0, federated tables allow access to the tables located on other databases on other servers.
19. What is SERIAL data type in MySQL? - BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT
20. What happens when the column is set to AUTO INCREMENT and you reach the maximum value for that table? - It stops incrementing. It does not overflow to 0 to prevent data losses, but further inserts are going to produce an error, since the key has been used already.
21. Explain the difference between BOOL, TINYINT and BIT. - Prior to MySQL 5.0.3: those are all synonyms. After MySQL 5.0.3: BIT data type can store 8 bytes of data and should be used for binary data.
22. Explain the difference between FLOAT, DOUBLE and REAL. - FLOATs store floating point numbers with 8 place accuracy and take up 4 bytes. DOUBLEs store floating point numbers with 16 place accuracy and take up 8 bytes. REAL is a synonym of FLOAT for now.
23. If you specify the data type as DECIMAL (5,2), what’s the range of values that can go in this table? - 999.99 to -99.99. Note that with the negative number the minus sign is considered one of the digits.
24. What happens if a table has one column defined as TIMESTAMP? - That field gets the current timestamp whenever the row gets altered.
25. But what if you really want to store the timestamp data, such as the publication date of the article? - Create two columns of type TIMESTAMP and use the second one for your real data.
26. Explain data type TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP - The column exhibits the same behavior as a single timestamp column in a table with no other timestamp columns.
27. What does TIMESTAMP ON UPDATE CURRENT_TIMESTAMP data type do? - On initialization places a zero in that column, on future updates puts the current value of the timestamp in.
28. Explain TIMESTAMP DEFAULT ‘2006:09:02 17:38:44′ ON UPDATE CURRENT_TIMESTAMP. - A default value is used on initialization, a current timestamp is inserted on update of the row.
29. If I created a column with data type VARCHAR(3), what would I expect to see in MySQL table? - CHAR(3), since MySQL automatically adjusted the data type.
ABOUT MY INTERVIEW:
1.First They asked explain about Urself briefly.
2. Then asked about mark variations in School and degree
3.Then asked me Y u came to Coputer rather tah science(becx basicall i was a science student in my ug)
4. Then ased abt area of intrest.(for mine Database)
5. what is Normalization. explain with example
(i explained upto 4 normal form)
6. what is Index.Explain
7.What is Triggers Diff between trigger and View
8.What is view .Write Syntax of Views.
9.What is cursors.explain
10.How to optimize the Querys.
11.Tel about ur Projects and explain that.
12.How to Modify that project
13.Joins In MySql
14.What is linear Datastrucure
15.what is linked list .Explain
16.Linked list is linear or non linear..
17.what is Stack and QUeue.
18.Write program for count the numers (with and without recruion)
oops....Thats it.. My interview got over ... me got selected..