Question

i need 4 paragraphs which explains in detail please ill vote up thansk

Write a detailed 4 paragraph discussion/summary on concepts discussed in Chapters 9 and 10 (Ullman). These concepts include how to connect to MySQL, what is a query, how is one executed, how to retrieve query results, updating records in a DB, sending data to a script, hidden form inputs and other relevant material learned You also must respond to a colleague's posting. This posting MUST be a at least a paragraph in length and should discuss your thoughts on the material presented by your colleague. It should NOT be a critique complimenting your colleague's posting

Answer 1

SQL-structured query language

It is the most widely used commercial relational data base language.

It was originally developed at IBM in the SEQUELXRM and system-R projects (1974-1977),other vendors introduced DBMS products based on SQL and it is now a de facto standard.

SQL continuous to evolve in response to changing needs in the database area.

The current ANSI/ISO standard for SQL:1999 standard.

1.how to connect to MySQL-

In ubuntu after installing the mysql server,

Go to the terminal and type sudo mysql

Then enter password

This will connect you to mysql.

Firstly database should be created.

Syntax is create database databasename;

mysql>use databasename;

Then you can create tables and so on in your data base.

2.what is query?

Ans:

Syntax of query explains its meaning through a conceptual evaluation strategy.

A conceptual evaluation strategy is a way to evaluate the query that is intended to be easy to understand rather than efficient.

A database management system (DBMS) would typically execute a query in a different and more efficient way.

The basic form of SQL query is

Select attribute-list

from relations-list

where conditions;

where attribute list is the set of attributes we want to display as output,relations-list or tables used for the queries and condition is the condition defined on attributes of a relation.

3.how is one executed?

Ans: when we write a query an execute it ,firstly from clause will be executed then

Where clause,group by clause,having clause,select clause,orderby clause

This is the order of execution of a query.

If where clause and having clause appear in the same query,sql apply where clause first followed by groupby followed by having.

A small example for how a query is executed:

Query:

select branch_name

From loan;

Here loan is the relation ,and branch_name is the attribute

So while executing the query first from clause will be executed then select clause will be executed.

4.how to retrieve query results?

Ans:

To retrieve the information from mysql database tables,select statement beggining with select keyword should be used.

Example: if we have created table and inserted values into tables ,if we want to see the table to be displayed

Then we need to use the syntax

select * from table name;

Then it will provide output.

* (Asterik )symbol indicates all attributes of a particular table.

If we want particular attributes ,we can mention only them and get the output.eg:

select branch_name ,ammount

from loan;

5.updating records in a database:

We can update our information in the database using the update syntax

update tablename set attr=value where condition;

Example:

update student set marks=83

where rno='18361A0503';

Using the update (DML-data manipulation language)command we can update the records of database.

In this we can connect to mysql and write queries and execute the queries .