Inner join

An inner join returns only the rows from each table that have matching values in the join columns. Any rows that do not have a match between the tables do not appear in the result table.

With an inner join, column values from one row of a table are combined with column values from another row of another (or the same) table to form a single row of data. SQL examines both tables specified for the join to retrieve data from all the rows that meet the search condition for the join. There are two ways of specifying an inner join: using the JOIN syntax, and using the WHERE clause.

Suppose you want to retrieve the employee numbers, names, and project numbers for all employees that are responsible for a project. In other words, you want the EMPNO and LASTNAME columns from the CORPDATA.EMPLOYEE table and the PROJNO column from the CORPDATA.PROJECT table. Only employees with last names starting with 'S' or later should be considered. To find this information, you need to join the two tables.