Can we use distinct and GROUP BY Together in Oracle?
yes. i realize that error that i did. when add distinct key word to all selected columns it works.
Which is better distinct or GROUP BY in Oracle?
DISTINCT implies you want a distinct set of columns. However, GROUP BY implies you want to compute some sort of aggregate value which you are not.
How do I count distinct rows in Oracle?
The COUNT() function accepts a clause which can be either ALL , DISTINCT , or * :
- COUNT(*) function returns the number of items in a group, including NULL and duplicate values.
- COUNT(DISTINCT expression) function returns the number of unique and non-null items in a group.
Is it better to use GROUP BY or distinct?
DISTINCT is used to filter unique records out of all records in the table. It removes the duplicate rows. SELECT DISTINCT will always be the same, or faster than a GROUP BY.
Can we use distinct with GROUP BY?
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.
How do I count distinct entries in SQL?
To count the number of different values that are stored in a given column, you simply need to designate the column you pass in to the COUNT function as DISTINCT . When given a column, COUNT returns the number of values in that column. Combining this with DISTINCT returns only the number of unique (and non-NULL) values.
Which is more efficient distinct or GROUP BY?
Why GROUP BY is faster than distinct?
DISTINCT would usually be faster than GROUP BY if a) there’s no index on that column and b) you are not ordering as well since GROUP BY does both filtering and ordering.
Does GROUP BY return distinct values?
The group by can also be used to find distinct values as shown in below query. The two queries return same result. The group by gives the same result as of distinct when no aggregate function is present.
Which one is faster count (*) or Count 1?
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.
How do I COUNT by group in SQL?
The SQL GROUP BY Statement The GROUP BY statement groups rows that have the same values into summary rows, like “find the number of customers in each country”. The GROUP BY statement is often used with aggregate functions ( COUNT() , MAX() , MIN() , SUM() , AVG() ) to group the result-set by one or more columns.
What does count distinct mean?
Count Distinct – Returns the number of unique values in a measure or dimension. When applied to a dimension, Tableau creates a new temporary column that is a measure because the result of a count is a number. You can count numbers, dates, Booleans, and strings. Null values are ignored in all cases.
How do you count distinct in SQL?
This function treats VARIANT NULL (JSON null) as SQL NULL.
What is CLOB datatype in Oracle with example?
CLOB. Stands for “Character Large Object.” A CLOB is a data type used by various database management systems, including Oracle and DB2. It stores large amounts of character data, up to 4 GB in size. Since CLOB data may be very large, some database management systems do not store the text directly in the table.
What is a distinct count?
What is a distinct count? “Distinct count” counts the number of distinct values of your column (SELECT DISTINCT ) “Unique count” counts the number of distinct values with only one instance. It is necessarily less or equal to “distinct counts” “Duplicate count” count the number of values appearing more than once.