Oracle FROM

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FROM clause is a mandatory clause in SELECT expression. It specifies the tables from which data is to be retrieved.

Syntax:

  1. FROM table_name...  
  2. Expressions...  

Oracle FROM Clause Example: (with one table)

Let's take an example to explain how to use FROM clause to retrieve data from one table. Consider a table "customers".

Customer table:

  1. CREATE TABLE  "CUSTOMERS"   
  2.    (    "NAME" VARCHAR2(4000),   
  3.     "AGE" NUMBER,   
  4.     "SALARY" NUMBER,   
  5.     "STATE" VARCHAR2(4000)  
  6.    )  
  7. /  

Customer Table

Execute this query:

  1. SELECT *  
  2. FROM customers  
  3. WHERE salary >= 20000  
  4. ORDER BY salary ASC;  

Output:

Oracle from example

Oracle FROM Clause Example: (with two tables)

Inner Join example:

Let's take two tables "suppliers" and "order1".

Suppliers:

Oracle Inner Join
Oracle Inner Join supplier

Order1:

Oracle Inner Join
Oracle Inner Join order

Execute the following query:

  1. SELECT suppliers.supplier_id, suppliers.supplier_name, order1.order_number  
  2. FROM suppliers  
  3. INNER JOIN order1  
  4. ON suppliers.supplier_id = order1.supplier_id;  

Output:

Oracle from example 5