Connection QueryImplementing a retrieval operation that retrieves data from two or more two tables and that appears in the result set from two or more than two tables is referred to as a join technique, or a technology that refers to the multiplication of data in two tables or more than two tables. Internal ConnectionThe inner join generates a third table in the data connection from the two tables, and the third table contains only the rows of data that meet the join criteria. Inside the connection, the inner join operator is used and the on keyword is used to specify the join condition. The silent connection type is in-time connected. The following syntax is in the format:
self-connect
connection operations can be made not only in different tables, but also within the same table, connecting different rows in the same table . a self-connection can be thought of as a connection between two copies of a table. In a self-join, you must specify two aliases for the table so that it becomes logically two tables .
External Connectionin an out-of-connection, not only the data that satisfies the criteria is included, but some of the data that does not meet the criteria is also displayed in the result set . It is important to note that outer joins can only be used in two different tables.
Database connection Query
