How does the join work?

How does a join work?

A JOIN clause is used to combine rows from two or more tables, based on a related column between them. Notice that the "CustomerID" column in the "Orders" table refers to the "CustomerID" in the "Customers" table. The relationship between the two tables above is the "CustomerID" column.

How does a union join work?

The Union operator combines the results of two or more queries into a distinct single result set that includes all the rows that belong to all queries in the Union. In this operation, it combines two more queries and removes the duplicates. For example, the table 'A' has 1,2, and 3 and the table 'B' has 3,4,5.

How does join work in databases?

Join is the widely-used clause in the SQL Server essentially to combine and retrieve data from two or more tables. In a real-world relational database, data is structured in a large number of tables and which is why, there is a constant need to join these multiple tables based on logical relationships between them.

What is the difference between the union and join?

The difference lies in how the data is combined. Joins combine data into new columns. If two tables are joined together, then the data from the first table is shown in one set of column alongside the second table's column in the same row. Unions combine data into new rows.