What is SQL?, SQL Process, Stages Of SQL What Can SQL do, Detailed Diagram is drawn as:, PL/SQL Advantages, Difference between SQL and PL/SQL

1. Prof. Neeraj Bhargava
Pooja Dixit
Department of Computer Science
School of Engineering & System Science
MDS, University Ajmer, Rajasthan, India
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2. What is SQL?
 SQL stands for Structured Query Language
 SQL lets you access and manipulate databases
 SQL became a standard of the American National Standards Institute
(ANSI) in 1986, and of the International Organization for Standardization
(ISO) in 1987
What Can SQL do?
 SQL can execute queries against a database
 SQL can retrieve data from a database
 SQL can insert records in a database
 SQL can update records in a database
 SQL can delete records from a database
 SQL can create new databases
 SQL can create new tables in a database
 SQL can create stored procedures in a database
 SQL can create views in a database
 SQL can set permissions on tables, procedures, and views
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3.  When you are executing an SQL command for any
RDBMS, the system determines the best way to carry
out your request and SQL engine figures out how to
interpret the task.
 There are various components included in this
process.
 These components are −
 Query Dispatcher
 Optimization Engines
 Classic Query Engine
 SQL Query Engine, etc.
 A classic query engine handles all the non-SQL
queries, but a SQL query engine won't handle logical
files.
 Following is a simple diagram showing the SQL
Architecture −
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To process an SQL statement, a DBMS performs the following five steps:
 The DBMS first parses the SQL statement. It breaks the statement up into
individual words, called tokens, makes sure that the statement has a
valid verb and valid clauses, and so on. Syntax errors and misspellings
can be detected in this step.
 The DBMS validates the statement. It checks the statement against the
system catalog. Do all the tables named in the statement exist in the
database? Do all of the columns exist and are the column names
unambiguous? Does the user have the required privileges to execute the
statement? Certain semantic errors can be detected in this step.
 The DBMS generates an access plan for the statement. The access plan is
a binary representation of the steps that are required to carry out the
statement; it is the DBMS equivalent of executable code.
 The DBMS optimizes the access plan. It explores various ways to carry
out the access plan. Can an index be used to speed a search? Should the
DBMS first apply a search condition to Table A and then join it to Table
B, or should it begin with the join and use the search condition
afterward? Can a sequential search through a table be avoided or
reduced to a subset of the table? After exploring the alternatives, the
DBMS chooses one of them.
 The DBMS executes the statement by running the access plan.

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7. PL/SQL offers the following advantages:
 Reduces network traffic This one is great advantages of PL/SQL. Because
PL/SQL nature is entire block of SQL statements execute into oracle
engine all at once so it's main benefit is reducing the network traffic.
 Procedural language support PL/SQL is a development tools not only for
data manipulation futures but also provide the conditional checking,
looping or branching operations same as like other programming
language.
 Error handling PL/SQL is dealing with error handling, It's permits the
smart way handling the errors and giving user friendly error messages,
when the errors are encountered.
 Declare variable PL/SQL gives you control to declare variables and access
them within the block. The declared variables can be used at the time of
query processing.
 Intermediate Calculation Calculations in PL/SQL done quickly and
efficiently without using Oracle engines. This improves the transaction
performance.
 Portable application Applications are written in PL/SQL are portable in
any Operating system. PL/SQL applications are independence program
to run any computer.
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9. 1. What is structural query language?explain.
2. Explain the sql process.
3. Difference between procedural and
nonprocedural language.
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