A join is the ability to connect two or more database tables or views for retrieval of data. The connection between the tables is a column in each table that contains identical information.
For example, there are two tables in a company database that include employee names and serial numbers. One table contains personnel information about each employee in the company, while the other contains departmental information for the engineering organization, including the employees in each department and current departmental projects. The personnel table uses the column headings Employee_Name and Employee_ID for the names and ID numbers of the employees. The departmental table uses the column headings Department_Member and Employee_ID for the same information.
When two tables are joined in the SQL Statement Builder, a line connects the columns involved in the join. Two kinds of joins are possible: inner joins and outer joins. See the following for detailed information: