SQL Statements

SQL Statements

 

Here i am explaining some useful sql Statements of queries

·         SQL SELECT Statement

·         SQL SELECT DISTINCT Statement

·         SQL WHERE Clause or Condition

·         SQL AND Operator

 

Firstly i am creating the common table named Grahak for use in some of the sql statements which are explaining in this article

Table named Grahak with column and rows with Values

CustomerID	CustomerName	Contactnumber	Address	City	PostalCode	Country
1	Ram	9871234563	#47 Sector 22	Chandigah	160002	Japan
2	Sham	9876543216	#4110 Sector 122	Mohali	140002	India
3	Shivam	3278955152	#5 Sector 88	Gurgaon	180002	UAE
4	Ravi	2277894562	#5 Sector 48	Badlapur	220002	North korea

Different SQL Statements

1.    SQL SELECT Statement

The SELECT statement is used to fetch data from the database.

Syntax

SELECT column_first, column_second, column_third,  ...and so on
FROM table_name;

Here, column_first, column_second, column_third, ... and so on are the column names of the table you want to fetch data from.

The table_name presents the name of the table from where you want to fetch data.

Example

Fetch data from the Grahak table:

SELECT CustomerName, City FROM Grahak;

Below is a selection from the Grahak  table used in the example:-

Select ALL columns

If you want to fetch all columns, without mentioning all column name, you can use the SELECT * syntax:

Example

Fetch all the columns from the Customers table:

SELECT * FROM Grahak;

2.    SQL SELECT DISTINCT Statement

The SELECT DISTINCT statement is used to fetch only distinct (different) from the table

Example

Select all the different countries from the "Grahak" table:

SELECT DISTINCT Country FROM Grahak;

Syntax

SELECT DISTINCT column_first, column_second, column_third,  ...and so on
FROM table_name;

Count Distinct

By using the DISTINCT keyword in a function called COUNT, we can fetch the number of different countries from the Grahak table.

Example

SELECT COUNT(DISTINCT Country) FROM Grahak;

 

3.    SQL WHERE Clause or Condition

The WHERE clause or condition is used to filter records from the table.

It is used to fetch only those records from the table that accomplish a specific condition.

Example

Select all customers from India:

SELECT * FROM Grahak
WHERE Country='India';

 

SQL ORDER BY

The ORDER BY keyword is used to fetch the data in ascending or descending order from the table.

Example

Sort the products by price:

SELECT * FROM items
ORDER BY Price;

 

Syntax

SELECT column1, column2, ...
FROM table_name
ORDER BY column1, column2, ... ASC|DESC;

 

Syntax

SELECT column1, column2, ...
FROM table_name
WHERE condition;

Below is a selection from the items table used in the examples

 

ProductID	ProductName	SupplierID	CategoryID	Unit	Price
1	Apple	1	1	50	18
2	Orange	1	1	45	19
3	Banana	1	2	88	10
4	Water Melon	2	2	95	22

 

DESC

The ORDER BY keyword fetch the records with sorting  in ascending order by default. For sort the records of the table in descending order, use the DESC keyword.

Example

Sort the items from the table as highest to lowest price:

SELECT * FROM items
ORDER BY Price DESC;

 

Order Alphabetically

For string values the ORDER BY keyword will order alphabetically:

Example

Sort the items alphabetically by ProductName:

SELECT * FROM Products
ORDER BY ProductName;

Alphabetically DESC

To sort the table reverse alphabetically, use the DESC keyword:

Example

Sort the products by ProductName in reverse order:

SELECT * FROM items
ORDER BY ProductName DESC;

 

ORDER BY Several Columns

The following SQL statement selects all customers from the "items" table, sorted by the "Country" and the "CustomerName" column. This means that it orders by Country, but if some rows have the same Country, it orders them by CustomerName:

Example

SELECT * FROM items
ORDER BY Country, CustomerName;

 

Using Both ASC and DESC

The following SQL statement selects all customers from the "Customers" table, sorted ascending by the "Country" and descending by the "CustomerName" column:

Example

SELECT * FROM items
ORDER BY Country ASC, CustomerName DESC;

4.    SQL AND Operator

The WHERE clause can contain one or many AND operators.

The AND operator is used to filter records based on more than one condition, like if you want to return all Grahak  from Spain that starts with the letter 'G':

Example

Select all customers from Spain that starts with the letter 'G':

SELECT *
FROM Grahak
WHERE Country = 'India' AND CustomerName LIKE 'G%';

Syntax

SELECT column_first, column_second, column_third, ...and so on
FROM table_name
WHERE condition_first AND condition_second AND condition_third ... and so on;

To fetch the data from the table using And operatorall conditions must be true

The following SQL statement selects all fields from Grahak where Country is "India" AND City is "Chandigarh" AND CustomerID is higher than 50:

Example

SELECT * FROM Grahak
WHERE Country = 'India'
AND City = 'Chandigarh'
AND CustomerID > 50;