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Mệnh đề HAVING trong SQL cho phép bạn chỉ định điều kiện lọc mà kết quả nhóm xuất hiện trong kết quả. Mệnh đề WHERE đặt các điều kiện vào các cột đã chọn, trong khi mệnh đề HAVING đặt các điều kiện vào các nhóm được tạo bởi mệnh đề GROUP BY.
SQL HAVING Examples. The following SQL statement lists the number of customers in each country. Only include countries with more than 5 customers:
15 Οκτ 2024 · Lệnh Having trong SQL Server cho phép người dùng lọc các kết quả truy vấn dựa trên những hàm tổng hợp và theo nhóm mà không thể đạt được bằng mệnh đề WHERE (được dùng để lọc từng hàng riêng lẻ).
We can write a WHERE clause to filter out rows where the value of amount in the Orders table is less than 500: FROM Orders. WHERE amount < 500; . But with the HAVING clause, we can use an aggregate function like SUM to calculate the sum of amounts in the order table and get the total order value of less than 500 for each customer: FROM Orders.
The SQL HAVING clause is used to filter the results of a GROUP BY query based on the result of an aggregate function. It is similar to the WHERE clause but is specifically applied after grouping and aggregation, allowing you to filter on the results of aggregate functions like COUNT, SUM, AVG, and others.
This tutorial shows you how to use SQL HAVING clause to specify the condition for groups. It also explains the differences between HAVING and WHERE clauses.
Summary: in this tutorial, you will learn how to use the SQL Server HAVING clause to filter the groups based on specified conditions. The HAVING clause is often used with the GROUP BY clause to filter groups based on a specified list of conditions. The following illustrates the HAVING clause syntax: select_list. FROM . table_name. GROUP BY .
