All language subtitles for [SubtitleTools.com] What Is SQL- - Learning Oracle 12c [Video]_2

In this lesson, we're taking
a look at SQL, or S-Q-L.

And SQL stands for
Structured Query Language.

So why is this of interest
to a database administrator?

Well, primarily because
SQL is the language

of relational databases.

The purpose of SQL is to
manipulate relational data.

So we have relational
databases that

have tables and relationships
between those tables,

and SQL is a
specially-designed language

to operate with those tables.

When we talk about what is SQL?

It's important to
classify a little bit

about what it is not.

So SQL is not a
proprietary language

that is owned by any company.

When Oracle says that they're
the caretaker of a language

like Java, that's different
than their relationship

to SQL, because SQL
is built on a standard

by the ANSI's
standard organization.

So it's the American
National Standards Institute.

And they come up with
the standards for what

will be in the SQL language.

So no company-- no
relational database company--

owns SQL.

It's also not to be
confused with SQL Server.

SQL Server is a relational
database product

from Microsoft.

People refer to
it, often, as SQL,

and that can be very confusing.

SQL is a language.

It is a language to deal
with relational databases.

We classify it as a
fourth-generation language,

or 4GL.

So what do we mean by that?

A lot of the languages we think
of when we consider the term

"programming language" fall
into the category of a 3GL,

or third-generation language.

And those are languages
like C and C++ and Java.

In using a 3GL, you have much
more control and responsibility

for things like memory
usage with variables.

Fourth-generation languages
are meant to be easier to use.

They're supposed to be
closer to natural language.

So most people would find that
SQL is easier to learn than C

or C++.

SQL is classified
into sublanguages,

and each one of those
sublanguages kind of

covers a portion of the
language syntax itself.

So we'll take a look at these.

The first sublanguage is DML,
or Data Manipulation Language.

So this is going to be the
subsection of the language that

does things like selecting
data, or querying data.

So SELECT statements
are primarily

used in things like reporting.

It also is classified
as INSERTs--

so an INSERT statement.

So that is inserting
data into a table--

so inserting a row
or rows into a table.

DML also includes UPDATE.

So an UPDATE statement
allows us to modify data,

change existing data
that's in a table

into whatever is
the desired state.

And finally, DELETE--

DELETE is the removing of
a row or rows from a table.

So all of these three--

SELECT, INSERT,
UPDATE, and DELETE--

belong to the DML portion, or
the DML sublanguage of SQL.

The next sublanguage is DDL,
or Data Definition Language.

So this is going to
be the aspect of SQL

where we manipulate
database objects.

So those are going to be
where we create the definition

of those objects themselves.

So rather than selecting
data from an object

or inserting data
into an object,

here we're actually
creating the objects,

or we're dropping them, or
we're changing the objects

in some fundamental way.

So a CREATE TABLE
statement falls under DDL.

So CREATE TABLE would actually
create the column structure,

the storage structure of
a table for DML statements

to be able to manipulate data.

Something like a DROP INDEX
statement would be DDL--

dropping an existing
index in the database.

ALTER SEQUENCE-- SEQUENCE
is a database object

that contains a
sequential number that's

used usually in row data.

An ALTER SEQUENCE
would be considered

DDL, as would ALTER TABLE.

So those fall under the category
of Data Definition Language.

DCL-- now, DML and DDL
are pretty well-used terms

in referring to
sublanguages of SQL.

You hear the term
DCL less often.

So DCL will be Data
Control Language,

and here we're talking about
things like data access,

and primarily permissions.