EduQuiz

String-valued functions return NULL if the length of the result would be greater than the value of the max_allowed_packet system variable. For functions that operate on string positions, the first position is numbered 1.

1,ASCII(str)-Returns the numeric value of the leftmost character of the string str. Returns 0 if str is the empty string. Returns NULL if str is NULL. ASCII() works for characters with numeric values from 0 to 255.1. SELECT ASCII(’2′);

2,BIN(N)-Returns a string representation of the binary value of N, where N is a longlong (BIGINT) number. SELECT BIN(12);

3,BIT_LENGTH(str)-Returns the length of the string str in bits.SELECT BIT_LENGTH(’text’);

4,CHAR(N,…)–CHAR() interprets the arguments as integers and returns a string consisting of the characters given by the code values of those integers. NULL values are skipped.1.SELECT CHAR(77,121,83,81,’76′);SELECT INSERT(’Quadratic’, 3, 4, ‘What’);

5,INSERT(str,pos,len,newstr)–Returns the string str, with the substring beginning at position pos and len characters long replaced by the string newstr.

A Subquery is exactly what it sounds like: a SELECT query that is subordinate to another query. This unit covers the various concepts of subqueries.

1. The subquery as scalar operand: A scalar subquery is a simple operand, and you can use it almost anywhere a single column value or literal is legal, and you can expect it to have those characteristics that all operands have: a data type, a length, an indication whether it can be NULL, and so on.

2. Comparisons Using Subqueries: The output of the subqueries can be used to compare the output of the outer most queries. This can be done using various comparison operators like >, <, IN, and so on.

3. Subqueries with ANY, IN, and SOME: These type of subqueries can be used in cases where a set of values need to be compared and the output determined.

4. Subqueries with ALL: These type of subqueries can be used in cases where a set of values are the output generated by the inner or subqueries and the output is possible only if all the values match with the outer query.

5. Correlated Subqueries: Sometimes a situation arises in which a subquery uses a field from the main query in its clause. Such a reference by a subquery to a field in its enclosing query, is called an outer reference, and the corresponding subquery is called a correlated subquery, because it’s correlated with the result set of one or more of the queries enclosing it.

6. EXISTS and NOT EXISTS: The Exists operator can be used to check if a subquery produces any results at all. The NOT EXISTS operator is exactly the opposite of the output produced by NOT EXISTS.

7. Row Subqueries: A row subquery is a subquery variant that returns a single row and can thus return more than one column value.

7. Subqueries in the FROM Clause: Subqueries are legal in a SELECT statement’s FROM clause. Any columns in the subquery select list must have unique names.

Indexes are used to find rows with specific column values quickly. Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more is the cost. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks. If a multiple-column index exists on col1 and col2, the appropriate rows can be fetched directly. If separate single-column indexes exist on col1 and col2, the optimizer will attempt to use the Index Merge optimization, or attempt to find the most restrictive index by deciding which index finds fewer rows and using that index to fetch the rows.

Index Merge optimization: The Index Merge method is used to retrieve rows with several range scans and to merge their results into one. The merge can produce unions, intersections, or unions-of-intersections of its underlying scans. This access method merges index scans from a single table; it does not merge scans across multiple tables.MySQL uses indexes for these operations:

• To find the rows matching a WHERE clause quickly.

• To eliminate rows from consideration. If there is a choice between multiple indexes, MySQL normally uses the index that finds the smallest number of rows.

• To retrieve rows from other tables when performing joins. MySQL can use indexes on columns more efficiently if they are declared as the same type and size. In this context, VARCHAR and CHAR are considered the same if they are declared as the same size. For example, VARCHAR(10) and CHAR(10) are the same size, but VARCHAR(10) and CHAR(15) are not.

Comparison of dissimilar columns may prevent use of indexes if values cannot be compared directly without conversion. Suppose that a numeric column is compared to a string column. For a given value such as 1 in the numeric column, it might compare equal to any number of values in the string column such as ‘1′, ‘ 1′, ‘00001′, or ‘01.e1′. This rules out use of any indexes for the string column.

• To find the MIN() or MAX() value for a specific indexed column key_col. This is optimized by a preprocessor that checks whether you are using WHERE key_part_N = constant on all key parts that occur before key_col in the index. In this case, MySQL does a single key lookup for each MIN() or MAX() expression and replaces it with a constant. If all expressions are replaced with constants, the query returns at once.

The CHAR and VARCHAR types are similar, but differ in the way they are stored and retrieved. They also differ in maximum length and in whether trailing spaces are retained.

The CHAR and VARCHAR types are declared with a length that indicates the maximum number of characters you want to store. For example, CHAR(30) can hold up to 30 characters.

The length of a CHAR column is fixed to the length that you declare when you create the table. The length can be any value from 0 to 255. When CHAR values are stored, they are right-padded with spaces to the specified length. When CHAR values are retrieved, trailing spaces are removed unless the PAD_CHAR_TO_FULL_LENGTH SQL mode is enabled.

Values in VARCHAR columns are variable-length strings. The length can be specified as a value from 0 to 65,535. The effective maximum length of a VARCHAR is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used.

In contrast to CHAR, VARCHAR values are stored as a one-byte or two-byte length prefix plus data. The length prefix indicates the number of bytes in the value. A column uses one length byte if values require no more than 255 bytes, two length bytes if values may require more than 255 bytes.

If strict SQL mode is not enabled and you assign a value to a CHAR or VARCHAR column that exceeds the column’s maximum length, the value is truncated to fit and a warning is generated. For truncation of non-space characters, you can cause an error to occur (rather than a warning) and suppress insertion of the value by using strict SQL mode.

For VARCHAR columns, trailing spaces in excess of the column length are truncated prior to insertion and a warning is generated, regardless of the SQL mode in use. For CHAR columns, truncation of excess trailing spaces from inserted values is performed silently regardless of the SQL mode.

VARCHAR values are not padded when they are stored. Trailing spaces are retained when values are stored and retrieved, in conformance with standard SQL.

Security:

• A privilege and password system that is very flexible and secure, and that allows host-based verification.

• Passwords are secure because all password traffic is encrypted when you connect to a server.

Scalability and Limits:

• Handles large databases. We use MySQL Server with databases that contain 50 million records. We also know of users who use MySQL Server with 60,000 tables and about 5,000,000,000 rows.

• Up to 64 indexes per table are allowed (32 before MySQL 4.1.2). Each index may consist of 1 to 16 columns or parts of columns. The maximum index width is 1000 bytes (767 for InnoDB); before MySQL 4.1.2, the limit is 500 bytes. An index may use a prefix of a column for CHAR,VARCHAR, BLOB, or TEXT column types.

Connectivity:

• Clients can connect to MySQL Server using several protocols:

- Clients can connect using TCP/IP sockets on any platform.

- On Windows systems in the NT family (NT, 2000, XP, 2003, or Vista), clients can connect using named pipes if the server is started with the – enable-named-pipe option. In MySQL 4.1 and higher, Windows servers also support shared-memory connections if started with the – shared-memory option. Clients can connect through shared memory by using the – protocol=memory option.

- On Unix systems, clients can connect using Unix domain socket files.

• MySQL client programs can be written in many languages. A client library written in C is available for clients written in C or C++, or for any language that provides C bindings.

• APIs for C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl are available, allowing MySQL clients to be written in many languages.

• The Connector/ODBC (MyODBC) interface provides MySQL support for client programs that use ODBC (Open Database Connectivity) connections.

For example, you can use MS Access to connect to your MySQL server. Clients can be run on Windows or Unix. MyODBC source is available. All ODBC 2.5 functions are supported, as are many others.

• The Connector/J interface provides MySQL support for Java client programs that use JDBC connections. Clients can be run on Windows or Unix. Connector/J source is available.

• MySQL Connector/NET enables developers to easily create .NET applications that require secure, high-performance data connectivity with MySQL. It implements the required ADO.NET interfaces and integrates into ADO.NET aware tools. Developers can build applications using their choice of .NET languages. MySQL Connector/NET is a fully managed ADO.NET driver written in 100% pure C#.

Localization:

• The server can provide error messages to clients in many languages.

• Full support for several different character sets, including latin1 (cp1252), german, big5, ujis, and more. For example, the Scandinavian characters “å”, “ä” and “ö” are allowed in table and column names. Unicode support is available as of MySQL 4.1.

• All data is saved in the chosen character set.

• Sorting and comparisons are done according to the chosen character set and collation (using latin1 and Swedish collation by default). It is possible to change this when the MySQL server is started. To see an example of very advanced sorting, look at the Czech sorting code.

MySQL Server supports many different character sets that can be specified at compile time and runtime.

• As of MySQL 4.1, the server time zone can be changed dynamically, and individual clients can specify their own time zone.

In our college days, most of us used to feel helpless while writing custom essays. That’s because we may not understand the technique of writing essays. If you want to write custom essays, you have to make thorough research and use your writing skills. It is very essential to know the art of essay writing if you want to write quality essays. To write an essay, after choosing the topic you have to gather all the information regarding that topic.   For writing an essay on a given topic you need to take care of few things-:

• Introduction-: The first and most important part in writing an essay is introduction of the topic. Introduction in essay writing must be very attractive and eye catching.  For example, if you are writing an essay on poverty, then in the first paragraph, you may write about the introduction of poverty like some facts or you can even give some reports regarding poverty. You have to limit your introduction within 4-5 lines.
• Compiling body of essay -: After writing introduction, you have to start body of the essay. You may not have to use much detail. You only need to provide the relevant information only. It is very important in essay writing to make your essay interesting. For this purpose, you can add famous quotations and poetic lines in your essay. But you need to be careful that the lines you include must be relevant and related to the topic.
• Conclusion-: Conclusion plays a very important place in essay writing. It is very important that you finish your essay well. You need to sum up your essay in a few lines at the end. Proper finishing can make your essay attractive for readers.

By following these points, you can write a custom essay more properly and with a lot of ease.

People react differently in same situations. The reason behind different reactions is various dimensions of personality. These personality dimensions are referred to as Big Five. Psychologists have found these traits to be universal irrespective of caste, religion and culture. The behavior of an individual in a particular situation largely depends on these dimensions.

The Big Five traits are Openness, Conscientiousness, Extroversion, Agreeableness, and Neuroticism. These are universal personality traits present in each and every individual but in variable degrees. People who score high in openness are insightful, imaginative and have interests in various genres. Energetic, talkative and assertive come under the personality dimension of extraversion. Individual’s having high degree of conscientiousness is organized and methodic. Kind, affectionate and sympathetic person shows traits of agreeableness. Neuroticism is the last dimension of big five personality traits. This dimension is related to emotional stability and degree of negative emotions

Big five test is designed to measure the personality traits of an individual. Today big five test is widely used by employers to choose appropriate candidates for their organization. After having an overview of personality traits of candidates the employer can recruit them according to special traits required in specific job profiles.

The cost of studies is going higher day by day, which is leading to inability of many students to bear it. It is advisable to seek financial aids for meeting the expense of enrollment. Several institutional bodies offer grants for helping such students but to obtain such assistance, one requires fulfilling some eligibility criteria. ATB test is the pre requisite of acquiring financial support from colleges or associations. Without this certificate, you may not be able to apply for any such grant.

Taking any of tests that are meant to check your mental ability is not a cakewalk, especially when have resources to prepare for it. This test is framed to assess some skill of a candidate. Ability to benefit is one of such tests that are proposed at the time of enrollment. Students, who do not have a high school diploma and aim to apply for monetary help, choose this test to get things done. A computerized evaluation is designed to conduct this test but high school students are not supposed to take it. A test is meant to check one’s intelligence on various levels. ability to benefit test,  Student assessment helps the authorities know where a student stands and whether he/she deserves financial help for studying further or not.

Quizzes play a pivotal role in boosting the mental abilities of students and learners. An edu quiz specifically proves beneficial for instilling a desire to learn. There are few things that you need to keep in mind while organizing such a program. First of all an edu quiz ought to be subject specific. Keeping all kinds of questions cannot make a good quizzing format. It depends on the participants, whether a question should be kept or not. Various educational institutes and online study forums offers assistance for upgrading knowledge of people who indulge in educational quizzes.

There are various forms of education quiz that take place in a school or college. Such education based contests help students sharpen their mind and give them an opportunity to test their IQ. To practice for these educational quizzes, one can look for subject based objective test papers available on internet. These papers come with solved answers, which help you verify your replies. It is a great source of learning. An education quiz is usually subject based. For instance, mathematics quiz, science quiz, language quiz etc. It plays an important role in motivating students to work hard for gaining more knowledge.