📄️ Joins in SQL
In SQL, a JOIN clause is used to combine rows from two or more tables, based on a related column between them. It allows you to merge data from multiple different tables into a single result. This can be incredibly beneficial when you have data spread across different tables, but want to include it in a single query result for analysis or operations.
📄️ Inner Join
In this tutorial, we will cover the concept of Inner Join in PostgreSQL. An Inner Join is one of the several ways to combine rows from two or more tables based on a related column between them. It allows you to combine data from two or more tables in a single output based on a common column.
📄️ Left Join
In SQL, a Join operation combines rows from two or more tables based on a related column between them. There are several types of Join operations, such as Inner Join, Left Join, Right Join, and Full Join. In this article, we will be focusing on one of these operations: The Left Join.
📄️ Right Join
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📄️ Full Join
The SQL Full Join is a type of join that returns all records when there is a match in either the left (table1) or the right (table2) table records.
📄️ Self Join
A self join in SQL is a way to combine rows from a single table into a result set that includes rows that satisfy the join condition. This technique is useful when the data being compared is in the same table.
📄️ Union operation
In the realm of SQL, the UNION operator is used to combine the result-set of two or more SELECT statements. Each SELECT statement in the UNION must have the same number of columns. The columns should also have similar data types, and they must be in the same order.
📄️ Group By clause
Welcome to this tutorial on the GROUP BY clause in PostgreSQL. This clause is an essential part of SQL, especially when it comes to data analysis. It allows you to group rows that have the same values in specified columns into aggregated data, like sum, average, or count.
📄️ Having clause
In SQL, the HAVING clause is used in combination with the GROUP BY clause to filter the results of a GROUP BY operation. Similar to the WHERE clause, HAVING allows us to specify conditions that filter the results. However, while WHERE filters individual rows, HAVING filters groups.
📄️ Exists operation
In this tutorial, we'll be focusing on the EXISTS operation in SQL. The EXISTS operation is a Boolean operator that returns true or false. It's typically used in the WHERE clause to check if a row or set of rows exists, based on the subquery it operates on.
📄️ SQL functions
In SQL, a function is a stored procedure that you can use and reuse over and over again. Functions are subprograms that take inputs, process them, and return a result. SQL functions can be used to perform calculations on data, to modify individual data items, to manipulate the output, or to format dates and numbers.
📄️ SQL constraints
Understanding SQL constraints is crucial as they specify the rules concerning the data types in a table. They help ensure the accuracy and reliability of the data contained within the table. In this tutorial, we are going to explore the various types of SQL constraints and how they are used in PostgreSQL.