Skip to main content

Posts

Showing posts with the label how does inner join works

Inner Joins

A join that identifies combinations of matching rows from two tables is called an inner join. The joining is done by connecting one table, using the primary key, another table that references it with a foreign key. Inner joins may be written using two different syntaxes. One syntax lists the tables to be joined separated by a comma. The other uses the INNER JOIN keywords.  Comma Separated Inner Join To combine data from two or more tables to find the detail of records referenced in a foreign key , a table join must be performed. The most common way to do this is by specifying a list (comma separated) of tables in the FROM clause of the SELECT and using the WHERE clause to indicate the relationship between the tables. A simple question that might be asked about the information in the world database is, “What are the country and corresponding capital cities (along with ID)?” To answer that question, the following two individual queries could be executed… mysql> SELECT Na