Latest answer - MySQL is a relational database management system which........
Read answer
Latest answer - MySQL does not support a very large database size as efficiently........
Read answer
Latest answer - Access to the user table should never be given to avoid SQL injection attacks..........
Read answer
Latest answer - In MySQL MyISAM is the default storage engine. MyISAM tables........
Read answer
Latest answer - Tables that are present in the memory are called as HEAP tables. When creating a HEAP table........
Read answer
Latest answer - Query Cache in MySQL is used in scenarios when the same queries need to be executed..........
Read answer
Latest answer - Exception handling means changing the usual expected flow of the code..........
Read answer
Latest answer - MySQL has a unique storage engine architecture that makes it adaptable to most.........
Read answer
Latest answer - Transactions are better supported in Oracle as compared to Mysql..........
Read answer
Latest answer - A trigger is a set of code which is executed in response to some event. ..........
Read answer
Latest answer - CHAR_LENGTH includes leading and trailing blanks and the string-termination.......
Read answer
Latest answer - BIT data type can store up to 8 bytes from My SQL version 5.0.3.......
Read answer
Latest answer - Using Enum can restrict the number of values that can be allowed to go inside a table. If there is an ENUM for Colors .....
Read answer
Latest answer - Aggregate functions in MySQL are a group of functions that are used to operate.......
Read answer
Latest answer - While using transactions in MySQL a transaction –safe table type must.......
Read answer
Latest answer - Establishing connection to MySQL database using Mysql binary........
Read answer
Latest answer - MyISAM is faster than InnoDB in most of the cases.........
Read answer
Latest answer - When multiple applications need to perform common database operations........
Read answer
Latest answer - Primary key is used to uniquely identify a row in a table.........
Read answer
Latest answer - A transaction in MySQL is a set of SQL statements written to perform a specific task.........
Read answer
Latest answer - An index in MySQL can be added using ALTER statement in multiple ways as shown........
Read answer
Latest answer - Establishing connection to MySQL database using PHP can be done...........
Read answer
How will you export tables as an XML file in MySQL?
MYSQL’s query browser has a provision called “Export Result Set” which allows the tables to be exported as XML.
What is the use of i-am-a-dummy flag in MySQL?
Using the i-am-dummy flag makes the SQL engine refuse any Updates or deletes to execute if the WHERE clause is not present. It is very useful when using delete statements. Using i-am-dummy flag will not allow the following statement to execute:
Delete from employee;
What are the differences between MySQL_fetch_array(), MySQL_fetch_object(), MySQL_fetch_row()?
Mysql_fetch_object returns the result from the database as objects while mysql_fetch_array returns result as an array. This will allow access to the data by the field names. E.g. using mysql_fetch_object field can be accessed as $result->name and using mysql_fetch_array field can be accessed as $result->[name]. mysql_fetch_row($result):- where $result is the result resource returned from a successful query executed using the mysql_query() function.
Example:
$result = mysql_query(“SELECT * from students);
while($row = mysql_fetch_row($result))
{
Some statement;
}
What is difference between mysql_connect and mysql_pconnect?
Mysql_connect() opens a new connection to the database while mysql_pconnect() opens a persistent connection to the database. This means that each time the page is loaded mysql_pconnect() does not open the database. Mysql_close() cannot be used to close the persistent connection. Though it can be used to close mysql_connect().
What is MySQL data directory? How to determine the location of the data directory?
MySQL stores its data on the disk on the data dictionary. Each subdirectory under this data dictionary represents a MySQL database, inside those directories. By default the information managed my MySQL = server mysqld is stored in data directory.A default location of data directory in windows is C:\mysql\data or C:\Program Files\MySQL\MySQL Server 5.0 \data..
What you can use Regular Expression for in MySQL? Support your answer with an example.
Regular expressions in MySql are used in queries for searching a pattern in a string.
· * Matches 0 more instances of the string preceding it.
· + matches 1 more instances of the string preceding it.
· ? Matches 0 or 1instances of the string preceding it.
· . Matches a single character.
· [abc] matches a or b or z
· | separates strings
· ^ anchors the match from the start.
REGEXP can be used to match the input characters with the database.
Example:
The following statement retrieves all rows where column employee_name contains the text 1000 (example salary):
Select employee_name
From employee
Where employee_name REGEXP ‘1000’
Order by employee_name
“.” Can be used to match any single character. “|” can be used to match either of the two strings
MySQL disadvantages - September 30, 2009 at 18:00 pm by Vidya Sagar
How will you export tables as an XML file in MySQL?
From the command prompt type the following statement:
mysql -u test --xml -e 'SELECT * FROM t1' > t1.xml
where ‘ –u test ‘ is the user name, --xml indicates the type of the file is xml, -e for export
What is the use of i-am-a-dummy flag in MySQL?
The flag i-am-a-dummy flag makes the MySQL engine to deny the UPDATE and DELETE commands unless the WHERE clause is present.
What are the differences between MySQL_fetch_array(), MySQL_fetch_object(), MySQL_fetch_row()?
The mysql_fetch_object() returns the result from the database as an object.
Ex: $result->name
The mysql_fetch_array() returns the result from the database as an associative array or numeric array or both by using mysql_NUM or mysql_ASSOC options.
EX: $result[0] ,$result['name']
The mysql_fetch_row() returns the result from the database as a numeric array.
Ex: $result[0]
What is difference between mysql_connect and mysql_pconnect?
Mysql_connect:
- Opens a new connection to the database
- The database connection can be closed
- Opens the page every time the page is loaded.
Mysql_pconnect:
- Opens a persistent connection to the database.
- The database connection can not be closed.
- The page need not be opened every time the page is loaded.
What is MySQL data directory? How to determine the location of the data directory?
MySQL data directory is most important location in which all MySQL databases are stored. The default data directory is located in the file mysql.lf.
If the out of the space is the issue, then the directory need to be moved another location. Before moving, the database need to be closed. After moving the MySQL configuration file need to be edited. Look for the ‘datadir’ entry and change the path to the new directory.
What you can use Regular Expression for in MySQL? Support your answer with an example.
Regular expressions are a set of characters. Regular expressions are used for finding certain sequences in strings.
The following are the regular expression characters:
- * Represents matching characters that are 0 or more occurrences of the string that precedes it.
- + Represents matching characters that are 1 or more occurrences of the string that precedes it.
- ? Represents matching characters that are 0 or 1 occurrences of the string that precedes it.
- . Represents single character pattern matching.
- [abc] Represents matching characters that is either a or b or c
- | Used for separation of strings
- ^ Finds the matching pattern starting from the beginning.
To match the input characters with database tables, REGEXP is used. For example:
Select cityname from territories where cityname REGEXP ‘^(jo)*’;
The above query returns all city names that has the substring ‘jo’.
Is it required to use Index when the MySQL table has only 100 rows? Justify your answer
Can use rownum.
Which of the following is not a MySQL Operator?a. Between..and..,b. Like,c. IN,d. Is NULL
How to solve MySQL timeout issue?
How will you export tables as an XML file?
