Questions for having clause and where clause
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I have a very simple question. I am using Mysql bench, and i had a data which likes below:
dateordered_new orderstatus orders 2016-06-23 23:19:23 returned 8 2016-06-01 23:19:23 completed 12 2016-06-22 23:19:23 returned 9 2016-06-04 23:19:23 completed 27 ...etc...
The question is simple, I want to show the amount of orders which has been returned in each month.
And here is my query:
select month(dateorderednew) as Month, sum(orders) as return_orders from table_a group by month having orderstatus='returned;
Considering the difference between where clause and having clause, my syntax should be worked. However, the system told me that "Error Code: 1054. Unknown column 'orderstatus' in 'having clause'" And it was wired.
However, when I modified my query like this:
select month(dateorderednew) as Month, sum(orders) as return_orders from table_a where orderstatus='returned group by month;
And it worked.
So, it was really confusing. I think having clause should follow by the group by statement. But I cannot answer why this case happened?
Do you guys have any idea for this?
In your situation, you should use a
select month(dateorderednew) as Month, sum(orders) as return_orders from table_a where orderstatus='returned' group by month
Because you want to filter rows from the table before they are aggregated.
You only use
having clause when you want to filter on an aggregate value, eg
select month(dateorderednew) as Month, sum(orders) as return_orders from table_a group by month having sum(orders) > 10
However, mysql is flexible and allows you to use a
having on a non-aggregate value.
Difference between WHERE vs HAVING clause in , What is the difference between having clause and where clause? A HAVING clause is like a WHERE clause, but applies only to groups as a whole (that is, to the rows in the result set representing groups), whereas the WHERE clause applies to individual rows. A query can contain both a WHERE clause and a HAVING clause.
HAVING is used to filter out results of aggregations, like
WHERE is used to filter on non-aggregate columns.
For example, you can do this:
select month(dateorderednew) as Month, sum(orders) as return_orders from table_a WHERE orderstatus='returned' group by month having sum(orders) < 100
Having (SQL), What is difference between WHERE and HAVING clause in SQL is one of the most popular question asked on SQL and database interviews, especially to The Group by clause is often used to arrange identical duplicate data into groups with a select statement to group the result-set by one or more columns. This clause works with the select specific list of items, and we can use HAVING, and ORDER BY clauses. Group by clause always works with an aggregate function like MAX, MIN, SUM, AVG, COUNT.
You have to replace the condition mentioned the having clause with where clause. Because
having clause filter the data on aggregated group and
where clause filter the data on whole record set.
Try the below SQL:
Select month(dateorderednew) as Month, sum(orders) as return_orders from table_a where orderstatus='returned group by month;
SQL - Having Clause, HAVING requires that a GROUP BY clause is present. WHERE and HAVING can be in the same query. The definitive guide for data professionals. Order today A WHERE clause is used is filter records from a result. The filter occurs before any groupings are made. A HAVING clause is used to filter values from a group. Before we go any further let’s review the format of an SQL Statement. It is. SELECT FROM WHERE GROUP BY HAVING
A 'WHERE' clause filters on individual row values...
where colname > 0
where colname = 'sometext'
A 'HAVING clause filters on a group or aggregate of a row and comes after the 'group by' statement if there is one...
group by colname having count(*) > 0
group by colname having sum(colname) < 1
Use HAVING and WHERE Clauses in the Same Query, In this tutorial, you will learn about the GROUP BY and HAVING Clause along with going over examples on how to put them to use. 2. HAVING Clause: HAVING Clause is used to filter the records from the groups based on the given condition in the HAVING Clause. Those groups who will satisfy the given condition will appear in the final result. HAVING Clause can only be used with SELECT statement. Let us consider Student table mentioned above and apply having clause on it:
SQL HAVING with GROUP BY, The difference between the having and where clause is best illustrated by an example. Suppose we have a table called emp_bonus as shown below. Note that the The HAVING clause works like the WHERE clause if it is not used with the GROUP BY clause. The difference between the HAVING clause and the WHERE clause is that the WHERE clause is used to filter rows, while the HAVING clause is used to filter groups of rows. Let’s take a look at several examples of using the HAVING clause.
GROUP BY and HAVING Clause in SQL, SQL - Having Clause - The HAVING Clause enables you to specify conditions that filter which group results appear in the results. December 22, 2017 1 Comment. WHERE and HAVING clause are mainly used in the statement of SQL queries, these allow us to restrict the combination in the result relation through using a specific predicate. The major difference between WHERE and HAVING is that WHERE clause specifies the conditions for selecting the tuples (rows) from the relations, including join conditions if needed.
Having vs. Where clause, A commonly asked interview question explained Where clauses filter the data as it is in the table. In contrast, having clauses filter the data after grouping and aggregation. Another way of putting it is that where works on individual records, but having works on grouped records. Filter Grouped Data with HAVING clause. The HAVING clause is a filter that acts similar to a WHERE clause, but the filter acts on groups of rows rather than on individual rows. In other words, the HAVING clause is used to qualify the results after the GROUP BY has been applied. The WHERE clause, in contrast, is used to qualify the rows that are returned before the data is aggregated or