SQL JOIN with FROM/WHERE

Joining tables with SQL FROM/WHERE.

  • A skeleton version of FROM/WHERE join syntax is this:

    SELECT select_list
    FROM table_1, table_2 [, table_3]...
    WHERE [table_1.]column  join_operator  [table_2.]column
    [AND search_conditions ]
    [ORDER BY  column1, column2, ... ]
    Example:
    SQL server, MySQL, Oracle, PostgreSQL :
    select  First_name "First name", Last_name "Last name",
      email, Telephone_type "Phone type",
      Telephone_number as "Phone number"
     from customers c, telephones t
     where c.customer_id=t.customer_id
     and Telephone_type<>'Unknown'
     order by Last_name;
  • This is a SELECT where we joins Customers table with the Telephones table using the Customer_id column, which exists in both tables, to connect the tables.
  • We lists the name, email, telephone type and the phone number for those that have known telephone_types.
    The result should be:
    First name Last name email Phone type Phone number
    Judith Bowman J.Bowman@imb.com Cell (371) 153-54
    Judith Bowman J.Bowman@imb.com Work (371) 143-54
    Ricard Nixon Ricard.Nixon@hotmail.com Work (978) 667-94
    Ricard Nixon Ricard.Nixon@hotmail.com Home (978) 667-94
    Robert Redford R.Redford@google.com Home (679) 234-94
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