Having Clause in MySQL

In MySQL, The "HAVING" clause is used in conjunction with the "GROUP BY" clause to filter the results of a grouped query based on a specified condition.

It is similar to the "WHERE" clause but is used specifically with grouped data.

The "HAVING" clause is particularly useful when we want to filter the result set based on aggregate values (like averages, counts, and sums) after using the "GROUP BY" clause.

It is important to note that while the "WHERE" clause filters rows before they are grouped, the "HAVING" clause filters groups after they have been formed.

Having Syntax In MySQL:

SELECT column1, aggregate_function(column2)
FROM tableName
GROUP BY column1
HAVING condition;

column1: The column by which we want to group the results.
aggregate_function(column2): An aggregate function applied to another column within each group.
tableName: The name of the table from which we want to retrieve data.
HAVING: Specifies the condition to filter the groups.

Having Clause with Count Function In MySQL:

SELECT category, COUNT(*) AS category_group_wise
FROM products
GROUP BY category
HAVING COUNT(*) > 2;

The above query groups the `products` on the category column and calculates the Count of each `category`.
Then we have added the `Having` Clause which will filter the results to include only groups with a `count` greater than `2`.

Having Clause with AVG Function In MySQL:

Example:

SELECT category, AVG(product_price) AS avg_price
FROM products
GROUP BY category
HAVING avg_price > 3000;

The above query groups the `products` on the category column and calculates the `AVERAGE` price for each `category`.
Then we have added the `Having` Clause which will filter the results to include only groups with an `avg_price` greater than `3000`.

Having Clause with SUM Function In MySQL:

Example:

SELECT category, SUM(product_price) AS total_price_category_wise
FROM products
GROUP BY category
HAVING SUM(product_price) > 4000;

The above query groups the `products` on the `category` column and calculates the SUM for each `category`.
Then we have added the `Having` Clause which will filter the results to include only groups with a SUM of `product_price` greater than `4000`.

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