How can I count without group by?

4 Answers

select a, count(*) as c from mytable group by a where c > 1; You need to replace where with having in this case, as follows:
select a, count(*) as c from mytable group by a having c > 1; NB The following query form will also work:
select * from ( select a, count(*) as c from mytable group by a ) where c > 1;

Can select be used without from?

Explanation: “SELECT” clause cannot be used without clause “FROM”.

How do I JOIN two tables without joining?

Using the “FROM Table1, Table2” Syntax One way to join two tables without a common column is to use an obsolete syntax for joining tables. With this syntax, we simply list the tables that we want to join in the FROM clause then use a WHERE clause to add joining conditions if necessary.

Is JOIN necessary in SQL?

Using the SQL JOIN clause is necessary if you want to query multiple tables. It’s the nature of relational databases in general – they consist of data that’s usually saved in multiple tables; in turn, these form a database. Once you get familiar with basic SQL queries, it’s wise to start learning the JOIN clause.

Can you use max without group by?

6 Answers. As per the error, use of an aggregate like Max requires a Group By clause if there are any non-aggregated columns in the select list (In your case, you are trying to find the MAX(Num) and then return the value(s) associated in the ID column).

Is value a keyword in SQL?

When you know you’re only returning a single value, then the VALUE keyword can help produce a leaner result set by avoiding the overhead of creating a full-blown object. The VALUE keyword provides a way to return JSON value.

Can you SELECT from multiple tables in SQL without join?

Yes, it is possible to join two tables without using the join keyword. Cross join is also known as cartesian join. If we specify the WHERE condition to the join which we just have seen, we can also convert the same cross join to inner join as well.

Is inner join necessary?

Generally, we use INNER JOIN when we want to select only rows that match an ON condition. If no rows match the ON condition, then it will not return any results. This can be somewhat stricter than using a LEFT JOIN .

How to select count and join over 3 tables?

You can do this by grouping and counting a distinct value. select count (distinct w.workflow_id), m.related_name,w.status from workflow as w, message as m, msg_bpm_rel as rel where rel.workflow_id = w.workflow_id and rel.message_id = m.message_id and m.adapter = ‘PE’ group by m.related_name, w.status My first attempt at getting the query to work.

How to count when joins are involved in MySQL?

Counting in MySQL When Joins are Involved. 1 Attempt 1: COUNT with JOIN. For the moment, lets focus on just getting the post count by user. We might be tempted to try JOINing the two tables and 2 Attempt 2: COUNT with LEFT JOIN. 3 Attempt 3: SUM/IF, and LEFT JOIN. 4 The solution: Subqueries and COALESCE.

What to do when a table join is null?

Another way we can achieve what we want (for a single table join) is to use SUM/IF: Here we’re saying “When the post id is null, give it a 0, otherwise a 1, then sum the results” which gives us the correct count.

When to use a group by for the Count?

If you have multiple columns in the where clause of the subquery, the query would probably benefit from a single combined index on all of those columns. You can still use a GROUP BY for the count, you just need to JOIN it back to your original table to get all the records, like this:

How can I count without group by?