Basics of Oracle SQL

Before stepping into the course, we need to know the basics of Oracle SQL, because it is very important to learn any course from the scratch.

What is SQL ?

SQL stands for Structured Query Language, which is used to interact with any databases. And it is standard language used to store, manipulate and also to retrieve the data.

Why basics of Oracle SQL is Important ?

Actually, this basics moreover helps you to crack oracle certification courses. As per the interview point of view, basics tells how the candidate answering for the questions.

Terms to understand about basics of Oracle SQL

The below list of terms are very essential to know everyone and it's very easy to understand.

Important Terms	Meaning
Schema	It is called as User, that one who signed in your database Ex: dev, sys, HR
Schema Objects	The objects which are used to access for the particular user (schema) Ex: Tables, synonyms, materialized views, sequence etc.
Data Dictionary	It is used to store the information's about the user and schema objects and other storage details.
Result set	Output of the particular query [Output]
Records	Rows which are seen in the table.
Fields	Columns which are seen in the table.
Database	It is used to store information.

----> USER is a schema

Understanding the SQL Query

It is first and foremost we need to understand the keyword of the particular SQL query, which includes writing code and execution code.

Keywords used in SQL Query

Clause	Meaning
SELECT	It is used to retrieve the data, based on the user requirement here we can to mention columns
FROM	It is used to represent table information.
WHERE	Based on our requirement we can give conditions by using any operators
GROUP BY	Grouping the records if there is any records belongs to same group
HAVING	If there are any group functions there means while we are trying to give conditions this will be used.
ORDER BY	It is used for sorting the records.

* represents -----> all columns while writing a query.

SQL query writing Order and execution order.

Writing Order => When you are writing any sql query means that should be in this order only.

Execution Order => how SQL engine reads your query by this order.

Writing Order	Execution Order
SELECT	FROM
FROM	WHERE
WHERE	GROUP BY
GROUP BY	HAVING
HAVING	SELECT
ORDER BY	ORDER

Important Standards

1, You can able to type your query in multiple lines

2, Nothing is CASE SENSITIVE in oracle EXCEPT data (which are available inside the records)

just see the data in the below query, you can't able to write 'KAVI', because the data is in 'kavi' lower case format only

3, Data Format sensitive

Default date format => DD-MON-YY

4, Always finish your query in semicolon (;)

Query:

Better Query writing person should always maintain the discipline in query writing like this ....

SELECT *

FROM orders;

Here orders is table which is represented by FROM clause, and * represents all columns, so we are selecting the all columns in SELECT clause.

----- Output for the above query

SELECT name, debit

FROM orders;

Here orders is table which is represented by FROM clause, and name and debit represents required columns in a table, so we are selecting these two columns in SELECT clause.

--------- Output for the above query

Now, you are clear in writing SQL query, so keep on practicing...

Thanking Notes

I hope now you are cleared with some basic understanding in Query, so practice well that is more important.

If you having any query related to the above post means kindly comment below, else chat directly to our official mail.

-------End of basics of Oracle SQL-----

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