How To Use Distinct In Sql?

How do you use distinct in SQL?

SQL SELECT DISTINCT Statement

  • SELECT DISTINCT returns only distinct (different) values.
  • SELECT DISTINCT eliminates duplicate records from the results.
  • DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc.
  • DISTINCT operates on a single column. DISTINCT for multiple columns is not supported.

What does the distinct clause do?

The SQL DISTINCT clause is used to remove duplicates from the result set of a SELECT statement.

Can we use multiple distinct in SQL?

DISTINCT on multiple columns. In SQL multiple fields may also be added with DISTINCT clause. DISTINCT will eliminate those rows where all the selected fields are identical.

What is Count distinct in SQL?

Difference between SELECT COUNT, COUNT(*) and SQL COUNT distinct. It returns the total number of rows after satisfying conditions specified in the where clause. It gives a distinct number of rows after eliminating NULL and duplicate values. It eliminates the NULL values in the output.

How do I find duplicates in SQL?

How it works:

  1. First, the GROUP BY clause groups the rows into groups by values in both a and b columns.
  2. Second, the COUNT() function returns the number of occurrences of each group (a,b).
  3. Third, the HAVING clause keeps only duplicate groups, which are groups that have more than one occurrence.

How do you remove duplicates without using distinct?

Method 1: SELECT col1, col2, col3 ….. –(list all the columns for which you want to eliminate duplicates) FROM (SELECT col1, col2, col3,….. –(list all the columns as above), COUNT(*) FROM table) Method 2: SELECT col1, col2, col3 ….. –(list all the columns for which you want to eliminate duplicates) FROM table UNION

What is the difference between unique and distinct?

Unique and Distinct are two SQL constraints. The main difference between Unique and Distinct in SQL is that Unique helps to ensure that all the values in a column are different while Distinct helps to remove all the duplicate records when retrieving the records from a table.

How does distinct keyword work?

Introduction to SQL Server SELECT DISTINCT clause

The query returns only distinct values in the specified column. In other words, it removes the duplicate values in the column from the result set. In other words, the DISTINCT clause treats all NULL “values” as the same value.

Does Count distinct include Null?

COUNT(expression) like all aggregate functions, can take an optional DISTINCT clause. The DISTINCT clause counts only those columns having distinct (unique) values. COUNT DISTINCT does not count NULL as a distinct value. The ALL keyword counts all non-NULL values, including all duplicates.

How do I count duplicate rows in SQL?

How it works:

  • First, the GROUP BY clause groups the rows into groups by values in both a and b columns.
  • Second, the COUNT() function returns the number of occurrences of each group (a,b).
  • Third, the HAVING clause keeps only duplicate groups, which are groups that have more than one occurrence.

How do I count rows in SQL?

The COUNT() function returns the number of rows that matches a specified criteria.

  1. SQL COUNT(column_name) Syntax. The COUNT(column_name) function returns the number of values (NULL values will not be counted) of the specified column:
  2. SQL COUNT(*) Syntax.
  3. SQL COUNT(DISTINCT column_name) Syntax.

Can we apply distinct two columns?

Answer. Yes, the DISTINCT clause can be applied to any valid SELECT query. It is important to note that DISTINCT will filter out all rows that are not unique in terms of all selected columns.