Showing posts with label SQL. Show all posts
Showing posts with label SQL. Show all posts

December 02, 2019

Top 20 PHP Interview Questions and Answers



Ques: 1) What is CAPTCHA?

Answer: 

CAPTCHA stands for Completely Automated Public Turing Test to tell Computers and Humans Apart. To prevent spammers from using bots to automatically fill out forms, CAPTCHA programmers will generate an image containing distorted images of a string of numbers and letters. Computers cannot determine what the numbers and letters are from the image but humans have great pattern recognition abilities and will be able to fairly accurately determine the string of numbers and letters. By entering the numbers and letters from the image in the validation field, the application can be fairly assured that there is a human client using it.

 

BlockChain interview Questions and Answers

 

Ques: 2) What is meant by urlencode() and urldecode()?

Answer:

string urlencode(str)

When str contains a string like this “hello world” and the return value will be URL encoded and can be use to append with URLs, normally used to append data for GET like someurl.com?var=hello%world

string urldocode(str)

This will simple decode the GET variable’s value. Example: echo (urldecode($_GET_VARS[var])) will output “hello world”

 

C language Interview Questions and Answers

 

Ques: 3) What is difference between mysql_fetch_array(), mysql_fetch_row() and mysql_fetch_object()?

Answer:

mysql_fetch_array - Fetch the all matching records of results.

mysql_fetch_object - Fetch the first single matching record of results.

mysql_fetch_row - fetches a result row as array.

 

C++ language Interview Questions and Answers

 

Ques: 4) What is difference between srand & shuffle?

Answer:

The srand function seeds the random number generator with seed and shuffle is used for shuffling the array values.

shuffle - This function shuffles (randomizes the order of the elements in) an array. This function assigns new keys for the elements in array. It will remove any existing keys you may have assigned, rather than just reordering the keys.

srand - Seed the random number generator

 

Machine Learning Interview Questions and Answers

 

Ques: 5) How do you capture audio/video in PHP?

Answer:

You need a module installed - FFMPEG. FFmpeg is a complete solution to record, convert and stream audio and video. It includes libavcodec, the leading audio/video codec library. FFmpeg is developed under Linux, but it can be compiled under most operating systems, including Windows.

 

MySQL Interview Questions and Answers

 

Ques: 6) What's the difference between COPY OF A FILE & MOVE_UPLOAD_FILE in file uploading?

Answer:

Move: This function checks to ensure that the file designated by filename is a valid upload file (meaning that it was uploaded via PHP's HTTP POST upload mechanism). If the file is valid, it will be moved to the filename given by destination.

If filename is not a valid upload file, then no action will occur, and move_uploaded_file() will return FALSE.

Copy: Makes a copy of a file. Returns TRUE if the copy succeeded, FALSE otherwise.

 

PowerShell Interview Questions and Answers

 

Ques: 7) What is the difference between echo and print?

Answer:

Main difference between echo() and print() is that echo is just an statement not a function and doesn't return's value or it just prints a value whereas print() is an function which prints a value and also it returns value.

We cannot pass arguments to echo since it is just a statement whereas print is a function and we can pass arguments to it and it returns true or false. print can be used as part of a more complex expression whereas echo cannot. echo is marginally faster since it doesn't set a return value.

 

Python Interview Questions and Answers

 

Ques: 8) What is the difference between require() and include()?

Answer:

Both of these constructs includes and evaluates the specific file. The two functions are identical in every way except how they handle failure. If filepath not found, require() terminates the program and gives fatal error, but include() does not terminate the program; It gives warning message and continues to program.

include() produces a Warning while require() results in a Fatal Error if the filepath is not correct.

 

Python Pandas Interview Questions and Answers


Ques: 9) How do we know properties of the browser?

Answer:

You can gather a lot of information about a person's computer by using $_SERVER['HTTP_USER_AGENT']. This can tell us more about the user's operating system, as well as their browser. For example I am revealed to be Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en) AppleWebKit/418 (KHTML, like Gecko) Safari/417.9.3 when visiting a PHP page.

This can be useful to programmers if they are using special features that may not work for everyone, or if they want to get an idea of their target audience. This also is important when using the get_browser() function for finding out more information about the browser's capabilities. By having this information the user can be directed to a version of your site best suited to their browser.

get_browser() attempts to determine the capabilities of the user's browser. This is done by looking up the browser's information in the browscap.ini file.

echo $_SERVER['HTTP_USER_AGENT'] . "<hr />\n";

$browser = get_browser();

foreach ($browser as $name => $value)  { echo "<b>$name</b> $value <br />\n";

 }

 

SQL Server Interview Questions and Answers

 

Ques: 10) What is difference between require_once(), require(), include(). Because all these function are used to call a file in another file.

Answer:

Difference between require() and require_once(): require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page).

So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don't include the file more times and you will not get the "function re-declared" error.

Difference between require() and include() is that require() produces a FATAL ERROR if the file you want to include is not found, while include() only produces a WARNING.

There is also include_once() which is the same as include(), but the difference between them is the same as the difference between require() and require_once().

 

Unix interview Questions and Answers

 

Ques: 11) What are the different types of errors in PHP?

Answer:

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although you can change this default behavior.

2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.

3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place.

 

C# Language Interview Questions and Answers

 

Ques: 12) How to Create a Cookie & destroy it in PHP?

Answer:

setcookie(”variable”,”value”,”time”);

variable - name of the cookie variable variable - value of the cookie variable time - expiry time

Example: setcookie(”test”,$i,time()+3600);

Test - cookie variable name

$i - value of the variable ‘Test’ time()+3600 - denotes that the cookie will expire after an one hour.

Destroy a cookie by specifying expiry time

Example: setcookie(”test”,$i,time()-3600); // already expired time

Reset a cookie by specifying its name only

setcookie(”test”);

 

CSS (Cascading Style Sheets ) Interview Questions and Answers

 

Ques: 13) What is the difference between the functions unlink and unset?

Answer:

unlink is a function for file system handling. It will simply delete the file in context. unset will set UNSET the specified variable.

unlink is used to delete a file. unset is used to destroy an earlier declared variable.

 

Robotic Process Automation(RPA) Interview Questions and Answers

 

Ques: 14) How do you know (status) whether the recipient of your mail had opened the mail i.e. read the mail?

Answer:

Embed an URL in a say 0-byte image tag may be the better way to go. In other word, you embed an invisible image on you html email and when the src URL is being rendered by the server, you can track whether your recipients have view the emails or not.

 

UX Design Interview Questions and Answers

 

Ques: 15) What is difference between mysql_connect and mysql_pconnect?

Answer:

mysql_connect opens up a database connection every time a page is loaded. mysql_pconnect opens up a connection, and keeps it open across multiple requests.

mysql_pconnect uses less resources, because it does not need to establish a database connection every time a page is loaded.

 

Docker Interview Questions and Answers

 

Ques: 16) What do you need to do to improve the performance (speedy execution) for the script you have written?

Answer:

If your script is to retrieve data from Database, you should use "Limit" syntax. Break down the non dynamic sections of website which need not be repeated over a period of time as include files.

 

Google Cloud Computing Interview Questions and Answers

 

Ques: 17) How do you insert single & double quotes in MySQL db without using PHP?

Answer: 

By using &amp; / &quote;

Alternately, escape single quote using forward slash \' . In double quote you don't need to escape quotes. Insert double quotes as "".

 

Azure Interview Questions and Answers

 

Ques: 18) What is the difference between strstr & stristr?

Answer:

For strstr, the syntax is: string strstr(string $string,string $str ); The function strstr will search $str in $string. If it finds the string means it will return string from where it finds the $str upto end of $string.

For Example:

$string = "http://yahoomail.com"; $str="yahoomail";

The output is "yahoomail.com". The main difference between strstr and stristr is of case sensitivity. The former consider the case difference and later ignore the case difference.

 

Linux Interview Questions and Answers

 

Ques: 19) What is the difference between explode and split?

Answer:

Split function splits string into array by regular expression. Explode splits a string into array by string.

For Example:

explode(" and", "India and Pakistan and Srilanka"); split(" :", "India : Pakistan : Srilanka");

Both of these functions will return an array that contains India, Pakistan, and Srilanka.

 

Data Science Interview Questions and Answers

 

Ques: 20) How can you avoid execution time out error while fetching record from MySQL?

Answer:

set_time_limit -- Limits the maximum execution time

For Example:

set_time_limit(0);

If you set to 0 you say that there is not limit.

 

Edge Computing Interview Questions and Answers

 


More Interview Questions and Answers:


Hadoop Technical Interview Questions and Answers

 

Hyperion Technical Interview Questions and Answers

 

Internet of Things (IOT) Interview Questions and Answers

 

C# Language Interview Questions and Answers

 


June 25, 2019

Top 20 Oracle PL/SQL Interview Questions and Answers


The following technical interview questions and answers are as per my experiences while working in Oracle PL/SQL projects. These may be useful for the freshers and experienced developers whenever facing PL/SQL interview.

 

Ques: 1. What is a mutating table error? How can you get this error?

Answer:

This error can come with triggers, whenever a trigger is trying to update a row it is currently using. The usual fix involves either use of views or temporary tables, so the database is selecting from one while updating the other. This is all because of the table is in middle of a transaction and referencing the same table again in the middle of the updating action causes the trigger to mutate.


Oracle Fusion Applications interview Questions and Answers


Ques: 2. What is the key difference between SQL and PL/SQL?

Answer:

SQL and PL/SQL are used to access data within Oracle databases. SQL is a limited language that allows you to directly interact with the database. You can write queries, manipulate objects and data of oracle database with SQL language. SQL doesn't include the programming concepts.

By using PLSQL, you can extract and manipulate the objects and data of oracle database. And can do all the things that normal programming languages can have, such as looping and controlled executions.

 

Oracle Accounts Payables Interview Questions and Answers

 

Ques: 3. What is the difference between Form triggers and Database level triggers?

Answer:

Form level triggers are use in forms and fire on any level like item level, row level or on block level on requirement of application. And database triggers are written in database directly and fire on behalf of any transaction like Insert, Update and delete on table automatically.

The key difference in form level triggers and database trigger is that form level trigger fire on user or application requirement and database triggers will fire automatically.

 

Oracle ADF Interview Questions and Answers                                 

 

Ques: 4. What is Pseudo column?

Answer:

Pseudo columns are database columns which are used for different purposes in oracle database.

ROWNUM, ROWID, SYSDATE, UID, USER, ORA_ROWSCN, SYSTIMESTAMP are pseudo columns in oracle database.

 

Oracle Access Manager Interview Questions and Answers


Ques: 5. What is exception handling in oracle? How can they be handled?

Answer:

When an error occurs, exception is raised normally, and execution is stopped. Control transfers to exception handling part. Exception is an error situation which arises during program execution. Exception handlers are routines written to handle the exception. The exceptions can be internally defined User-defined exception. In oracle, exception can be handled by using these exception statements:
EXCEPTION WHEN
DUP_VAL_ON_INDEX
NOT_LOGGED_ON
TOO_MANY_ROWS
VALUE_ERROR
NO_DATA_FOUND

 

Oracle Fusion HCM Interview Questions and Answers

 

Ques: 6. What is the key difference between OPEN-FETCH-CLOSE and FOR LOOP in CURSOR?

Answer:

A FOR LOOP in cursor implicitly declares its loop index as a %ROWTYPE record, opens a cursor, repeatedly fetches rows of values from the result set into fields in the record, and closes the cursor when all rows have been processed.

While using the OPEN-FETCH-CLOSE, we have to explicitly open the query and closing the query.

 

Oracle SCM Interview Questions and Answers

 

Ques: 7. What is Dynamic SQL? How can we use it in Oracle?

Answer: 

Dynamic SQL is used by PL/SQL to execute Data Definition Language (DDL) statements, Data Control (DCL) statements, or Transaction Control statements within PL/SQL blocks. These statements can, probably will change from execution to execution means change at runtime. These statements are not stored within the source code but are stored as character variables in the program.

    The SQL statements are created dynamically at runtime by using variables. This is used either using native dynamic SQL or through the DBMS_SQL package. Dynamic SQL supports all SQL data types.

 

Oracle Financials Interview questions and Answers

 

Ques: 8. What is the key difference Between Row Level Trigger and Statement Level Trigger?

Answer:

Row level trigger executes once for each row after or before in the DML event.  It can be defined by using FOR EACH ROW.

Statement Level trigger executes once after or before the DML event, it doesn’t matter many rows are affected by the DML event.  

 

Oracle Cloud Interview Questions and Answers


Ques: 9. What are the various steps included in the compilation process of a PL/SQL block?

Answer:

In the compilation process of a PL/SQL block, the syntax checking, binding, and p-code generation are involved. Syntax checking involves checking PL/SQL code for compilation errors. Syntax errors have been corrected, a storage address is assigned to the variables that are used to hold data for Oracle. This process is called binding. After binding, P-code is generated for the PL/SQL block. P-code is a list of instructions to the PL/SQL engine. For named blocks, p-code is stored in the database, and it is used the next time the program is executed.

 

Oracle SQL Interview Questions and Answers


Ques: 10. What packages have Oracle provided to PLSQL developers?

Answer:

Oracle provides the DBMS_ series of packages to PLSQL developers to smooth the programming. The below packages, the developer should be aware of:

DBMS_DDL

UTL_FILE

DBMS_OUTPUT

DBMS_JOB

DBMS_SQL

DBMS_PIPE

DBMS_TRANSACTION

DBMS_LOCK

DBMS_ALERT

DBMS_UTILITY

 

Oracle RDMS Interview Questions and Answers

 

Ques: 11. How can you protect your PL/SQL source code?

Answer:

Oracle provides a binary wrapper utility that can be used to scramble PL/SQL source code. This utility was introduced in Oracle 7.

This utility use human-readable PL/SQL source code as input and writes out portable binary object code. It can larger than the original in size. The binary code can be distributed without fear of exposing your used algorithms and methods. Oracle will still understand and know how to execute the code. Be careful, there is no "decode" command available. So, always keep your source code saved.

 

BI Publisher Interview Questions and Answers

 

Ques: 12. What are SQLCODE and SQLERRM in PLSQL? What is their importance in programming in PLSQL?

Answer:

In PLSQL, SQLCODE returns the value of the error number for the last encountered error. Whereas the SQLERRM returns the actual error message for the last encountered error. They are used in exception handling in PLSQL. These are very useful for the WHEN OTHERS exception.


Oracle 10g Interview Questions and Answers 



Ques: 13. What do you understand by cursors in PLSQL?


Answer:

Cursor is a pointer variable in a memory and use for data manipulation operations in PLSQL. Basically, cursor is a private SQL memory area. It is also used to improve the performance of the PLSQL block.

Two types of cursors are:

a). Implicit cursor: Implicit cursors use oracles to manipulate the data manipulation operations internally and developers have no control on this type of cursor. We use sql%notfound and sql%rowcount cursor attributes in implicit cursor.

b). Explicit cursor: Explicit cursors are created by the developers and can control it by using the Fetch, Open and close keywords.

There are five types of cursors attributes in PLSQL:

1). %isopen: used to verify whether this cursor is open or not.
2). %found: If cursor fetch the data then %found return true.
3). %notfound: If cursor fetches not data then %notfound return true.
4). %rowcount: It return no. of rows that are in cursor.
5). %bulk_rowcount: It is same as %rowcount but it is used in bulk.

 

Ques: 14. What is the Index-By-Tables in PLSQL?

Answer:

Index-By-Tables is also known as Associative Arrays. These are the sets of key-value pairs, where each key is unique and is used to locate a corresponding value in the array. The key can be an integer or a string.

Syntax : TYPE tab_type_name IS TABLE OF element type

               INDEX  BY  BINARY_INTEGER;

Ex:  TYPE DeptTabTyp IS TABLE OF Dept%ROWTYPE

         INDEX BY BINARY_INTEGER;

         Dept_tab DeptTabTyp;

 

Ques: 15. What do you understand by bulk binding?

Answer:

The bulk binding technique improves performance by minimizing the number of context switches between the PL/SQL and SQL engines. A DML operation statement can transfer all the elements of a collection in a single operation.

           For example, If the collection has 100 elements, It lets you to perform the 100 SELECT, INSERT, UPDATE, or DELETE statements using a single operation.              

 

Ques: 16. What do you under by AUTONOMOUS_TRANSACTION?

Answer:

The pragma AUTONOMOUS_TRANSACTION instructs the PL/SQL compiler to mark a PLSQL block as autonomous i.e. independent. Autonomous transactions let the compiler stop the main transaction to do DML operations, commit or roll back those operations, then resume the main transaction.

 

Ques: 17. What are the two components of LOB datatype in PLSQL?

Answer:

The two components of the LOB datatype in PLSQL are:

1). LOB locator: LOB Locator is a locator, which points to the location in the database where the actual value is stored. This value is stored along with the record in the table row and is like a pointer to the actual location of LOB value.

2). LOB value: It is referred to an actual image, file or value of the LOB datatype.

 

Ques: 18. What are cascading of triggers?

Answer:

If we insert data in one table and that table have trigger on it then trigger fire. And in this trigger, there is another table that we are using for inserting the data in it and this table has also trigger on it then this trigger also fire. This is called cascading of triggers.

 

Ques: 19. What do you understand by Table Functions in PLSQL?

Answer:

We can use the table function like the name of the database table. Table functions are functions that produce a collection of rows (either a nested table or a Varray) that can be queried like a physical database table or assigned to PL/SQL collection variable.

 

Ques: 20. What is the use of NOCOPY in PLSQL?

Answer:

In PLSQL programming, the NOCOPY is Compiler Hint. When the Parameters hold large data structures such as collections and records, all this time copying slows down the execution. To prevent this, we can specify NOCPY. This allows the PL/SQL Compiler to pass OUT and INOUT parameters by reference.