Yes, you can use COUNT() and DISTINCT together to display the count of only distinct rows. SELECT COUNT(DISTINCT yourColumnName) AS anyVariableName FROM yourTableName; … Display all records from the table using select statement.
How do you use count and distinct in the same query?
Syntax. SELECT COUNT(DISTINCT column) FROM table; This statement would count all the unique entries of the attribute column in the table . DISTINCT ensures that repeated entries are only counted once.
How do I count distinct values in SQL?
SQL to find the number of distinct values in a column
- SELECT DISTINCT column_name FROM table_name;
- SELECT column_name FROM table_name GROUP BY column_name;
Does Count Count distinct?
COUNT(ALL expression) evaluates expression for each row in a group, and returns the number of nonnull values. COUNT(DISTINCT expression) evaluates expression for each row in a group, and returns the number of unique, nonnull values.
Can I use distinct and group by together?
Well, GROUP BY and DISTINCT have their own use. GROUP BY cannot replace DISTINCT in some situations and DISTINCT cannot take place of GROUP BY. It is as per your choice and situation how you are optimizing both of them and choosing where to use GROUP BY and DISTINCT.
What does count distinct mean in SQL?
The COUNT DISTINCT function returns the number of unique values in the column or expression, as the following example shows. SELECT COUNT (DISTINCT item_num) FROM items; … If every column value is NULL, the COUNT DISTINCT function returns zero (0).
Does COUNT distinct include NULL?
COUNT DISTINCT does not count NULL as a distinct value. … The ALL keyword counts all non-NULL values, including all duplicates. ALL is the default behavior if no keyword is specified.
How can I COUNT distinct values of all columns in SQL?
3 Answers. The basic query is: select col001, count(*) from MyTable group by col001 union all select col002, count(*) from MyTable group by col002 union all . . . select col700, count(*) from MyTable group by col700 ; Not pleasant, but that is basically the query you need to run.
What is the difference between COUNT and distinct COUNT?
Count would show a result of all records while count distinct will result in showing only distinct count. For instance, a table has 5 records as a,a,b,b,c then Count is 5 while Count distinct is 3.
Why count 1 is faster than count (*)?
According to this theory, COUNT(*) takes all columns to count rows and COUNT(1) counts using the first column: Primary Key. Thanks to that, COUNT(1) is able to use index to count rows and it’s much faster.
What is the difference between Count Count distinct and count (*) in SQL When will these three commands generate the same and different results?
The simple answer is no – there is no difference at all. The COUNT(*) function counts the total rows in the table, including the NULL values. The semantics for COUNT(1) differ slightly; we’ll discuss them later. However, the results for COUNT(*) and COUNT(1) are identical.
Will distinct return NULL values?
In SQL, the DISTINCT clause doesn’t ignore NULL values. So when using the DISTINCT clause in your SQL statement, your result set will include NULL as a distinct value.
Is GROUP BY better than distinct?
While DISTINCT better explains intent, and GROUP BY is only required when aggregations are present, they are interchangeable in many cases.
Can we use distinct with GROUP BY in SQL?
Distinct is used to find unique/distinct records where as a group by is used to group a selected set of rows into summary rows by one or more columns or an expression. The functional difference is thus obvious. The group by can also be used to find distinct values as shown in below query.
Is it better to use GROUP BY or distinct?
Group by is expensive than Distinct since Group by does a sort on the result while distinct avoids it. But if you want to make group by yield the same result as distinct give order by null ..