DAY _ 5 : PostgreSQL Query Session.

 👊 WHERE  Clause 

• The SELECT  Statement returns all rows from one or more Columns in a table.
• To Retrieve rows that satify a specified condition, You use a WHERE Clause.

SYNTAX :

 SELECT * FROM Table_Name

WHERE 

First_Name = ' Phillip ' ;

                               OR

 SELECT *  FROM  Table_Name  WHERE   First_Name  =  ' Phillip ' ;

To Form the condition in the WHERE claiuse, You use comparison and logical Operators.

 Operator     |        Description

1.   =                          Equal
2.   >                         Greater Than
3.   <                         Less Than
4.   >=                     Greater Than or Equal
5.   <=                     Less Than or Equal
6.  < > or  !=        Not Equal
7.  AND                 Logical operator AND
8.  OR                     Logical Operator OR 
9.  IN                     Return true if a value matches any value in a list.
10.  BETWEEN   Return true if a value is between a range of values.
11.  LIKE             Return true if a value matches  a Pattern.
12.  IS NULL       Return true if a value is NULL.

Query Such as :

💬. Find List of Person Whose Name is 'Alex'  In Person Data sheet ?

SELECT * FROM Person

WHERE 

First_Name = 'Alex';

💬. Find List of Person Whose User_Id  is Between User_Id BETWEEN  '39Bf92EC3B4E930'  'acc9Ce48cE4e9aD'.

SELECT User_Id 

, First_Name

, Last_Name

, Sex

, Email

, Job_Title

FROM Person

WHERE User_Id BETWEEN  '39Bf92EC3B4E930'  AND  'acc9Ce48cE4e9aD';

💬. Find List of Person Whose Email End with ' .Com ' in Person Data sheet ?

SELECT User_Id 

, First_Name

, Last_Name

, Sex

, Email

, Job_Title

FROM Person

WHERE Email LIKE  '%.com';

💬. Find List of Person Whose Sex is  ' Female '  And Job Title is ' Engineer ' in Person Data sheet ?

SELECT User_Id 

, First_Name

, Last_Name

, Sex

, Email

, Job_Title

FROM Person

WHERE Sex = 'Female' AND Job_Title  LIKE  '%Engineer%' ;