PostgreSQL FROM Keyword

The PostgreSQL FROM keyword is used to specify the table from which the data should be selected or deleted.

Example:

Consider a database table called Employee with the following records:

• To select the Name and Salary data of the employees present in the Employee table, the following query can be used:

  SELECT Name, Salary FROM Employee;
  

  
  

  This will produce the result as shown below:

  Name	Salary
  John	3000
  Marry	2750
  Jo	2800
  Kim	3100
  Ramesh	3000
  Huang	2800

• To select all fields of the Employee table, the query will be:

  SELECT * FROM Employee;
  

  
  

  This result of the following code will be:

  EmpID	Name	City	Age	Salary
  1	John	London	25	3000
  2	Marry	New York	24	2750
  3	Jo	Paris	27	2800
  4	Kim	Amsterdam	30	3100
  5	Ramesh	New Delhi	28	3000
  6	Huang	Beijing	28	2800

• To delete the records of an employee whose EmpID is 5, the query will be:

  DELETE FROM Employee
  WHERE EmpID = 5;
  
  --See the result
  SELECT * FROM Employee
  

  
  

  Now the Employee table will contain following records:

  EmpID	Name	City	Age	Salary
  1	John	London	25	3000
  2	Marry	New York	24	2750
  3	Jo	Paris	27	2800
  4	Kim	Amsterdam	30	3100
  6	Huang	Beijing	28	2800

• Similarly, to delete the records of an employee where city starts with 'New', the query will be:

  DELETE FROM Employee
  WHERE City LIKE 'New%';
  
  -- see the result
  SELECT * from Employee;
  

  
  

  Now the Employee table will contain following records:

  EmpID	Name	City	Age	Salary
  1	John	London	25	3000
  3	Jo	Paris	27	2800
  4	Kim	Amsterdam	30	3100
  6	Huang	Beijing	28	2800