in this tutorial we learn to all about subquery Examples like as a SQL SELECT DISTINCT, COUNT and other aggregates, SQL Count Distinct Values, SQL COUNT( ) with All, SELECT AVG DISTINCT statement, SELECT MAX DISTINCT statement, SQL SELECT DISTINCT on multiple columns or many more.
Also Read: Nested Queries Subqueries in SQL Example
How do I return unique values in SQL?
SELECT DISTINCT returns only distinct (i.e. different) values.
The DISTINCT keyword eliminates duplicate records from the results.
DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc.
It operates on a single column. DISTINCT for multiple columns is not supported.
The SQL SELECT DISTINCT syntax
The general syntax is
SELECT DISTINCT column-name FROM table-name
Can be used with COUNT and other aggregates
SELECT COUNT (DISTINCT column-name) FROM table-name
SQL SELECT Examples
Question: List all unique distributor countries in alphabetical order.
SELECT DISTINCT Country FROM Distributor ORDER BY COUNTRY
Question: List the number of unique distributor countries
SELECT COUNT (DISTINCT Country) FROM Distributor
SQL Select Distinct Syntax
SELECT DISTINCT column FROM table_name;
SQL Count Distinct Values
SELECT Count(*) As DistinctGender FROM (SELECT DISTINCT CutomerGender FROM Buyer);
SQL Distinct Values with Count
SELECT DISTINCT BuyerGender, Count(*) as Occurs FROM Buyer GROUP BY BuyerGender;
SQL COUNT( ) with All
SELECT COUNT( ALL grade ) FROM buyer;
SELECT AVG DISTINCT statement
SELECT AVG(DISTINCT WorkId) FROM WorkerDetail WHERE WorkId= WorkId
SELECT MAX DISTINCT statement
SELECT MAX(DISTINCT WorkId) FROM WorkerDetail WHERE WorkId= WorkId
SQL SELECT DISTINCT on multiple columns
SELECT DISTINCT WorkName,WorkAddress,WorkCity FROM WorkerDetail Where WorkId=5
SELECT example without DISTINCT
SELECT * FROM WorkerDetail
I hope you get an idea about sql count distinct.
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