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Joining tables

Joining tables in SQL allows you to combine data from two or more tables into a single result set. This can be useful when you want to retrieve data from related tables and combine it in a meaningful way. There are several types of joins in SQL, including INNER JOIN, LEFT JOIN, and RIGHT JOIN.

Here are a few examples of joining tables in SQL:

  • INNER JOIN: returns only the rows that have matching values in both tables.

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SELECT table1.column1, table2.column2
FROM table1
INNER JOIN table2
ON table1.column1 = table2.column1;

  • LEFT JOIN: returns all rows from the left table and the matching rows from the right table. If there is no match in the right table, the result will contain NULL values.

    • sql
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    SELECT table1.column1, table2.column2
FROM table1
LEFT JOIN table2
ON table1.column1 = table2.column1;

  • RIGHT JOIN: returns all rows from the right table and the matching rows from the left table. If there is no match in the left table, the result will contain NULL values.

    • sql
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    SELECT table1.column1, table2.column2
FROM table1
RIGHT JOIN table2
ON table1.column1 = table2.column1;

    These are just a few examples of joining tables in SQL. The specific syntax and keywords used may vary depending on the database management system being used. It is important to note that when joining tables, it is essential to have a common column between the tables that can be used to join the data.



    Next: Subqueries

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