Why distinct is used in sql?

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SQL: DISTINCT ClauseDescription. The SQL DISTINCT clause is used to remove duplicates from the result set of a SELECT statement.Syntax. The columns or calculations that you wish to retrieve. …Note. …DDL/DML for Examples. …Example – Finding Unique Values in a Column. …Example – Finding Unique Values in Multiple Columns. …Example – How the DISTINCT Clause handles NULL Values. …

How do you select distinct in SQL?

SELECT DISTINCT columns FROM table… You can simply add the word DISTINCT after your SELECT keyword. You can also add the DISTINCT keyword inside aggregate functions: SELECT aggregate_function(DISTINCT column) FROM table… We’ll see some examples of this below. Invalid DISTINCT Syntax

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How do you count distinct in SQL?

Usage Notes ¶This function treats VARIANT NULL (JSON null) as SQL NULL.For more information about NULL values and aggregate functions, see Aggregate Functions and NULL Values.When this function is called as an aggregate function: If the DISTINCT keyword is used, it applies to all columns. …More items…

What is difference between unique and distinct in SQL queries?

Unique was the old syntax while Distinct is the new syntax,which is now the Standard sql.Unique creates a constraint that all values to be inserted must be different from the others. …Example: SELECT DISTINCT names FROM student ;CREATE TABLE Persons ( Id varchar NOT NULL UNIQUE, Name varchar (20) );

How to use all the different joins in SQL?

Use the JOIN keyword to specify that the tables should be joined. Combine JOIN with other join-related keywords (e.g. INNER or OUTER) to specify the type of join. The semantics of joins are as follows (for brevity, this topic uses o1 and o2 for object_ref1 and object_ref2, respectively). Join Type.


More about Why distinct is used in sql?


1. SQL – Distinct Keyword

The SQL DISTINCT keyword is used in conjunction with the SELECT statement to eliminate all the duplicate records and fetching only unique records. There may be a situation when you have multiple duplicate records in a table. While fetching such records, it makes more sense to fetch only those unique records instead of fetching duplicate records.

From www.tutorialspoint.com

3. How to use distinct in SQL – javatpoint

SQL DISTINCT clause is used to remove the duplicates columns from the result set. The distinct keyword is used with select keyword in conjunction. It is helpful when we avoid duplicate values present in the specific columns/tables. The unique values are fetched when we use the distinct keyword. SELECT DISTINCT returns only distinct ( different) values.

From www.javatpoint.com

4. SQL: DISTINCT Clause – TechOnTheNet

When more than one expression is provided in the DISTINCT clause, the query will retrieve unique combinations for the expressions listed. 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 …

From www.techonthenet.com

5. SQL SELECT DISTINCT: Performance Best Practices

Sep 06, 2021 · Before we dive deeper, let’s recall what the SQL SELECT DISTINCT statement is. A database table can include duplicate values for many reasons, but we may want to get the unique values only. In this case, SELECT DISTINCT comes handy. This DISTINCT clause makes the SELECT statement fetch unique records only.

From codingsight.com

6. sql – Should I use distinct in my queries – Stack Overflow

Nov 10, 2015 · As mentioned in some of the answers, DISTINCT (and sometimes wide GROUP BYs) often gets used when somebody hasn’t completely understood the datamodel, and wishes to avoid duplicates – which are usually better dealt with in another fashion (more restrictive joins, pre-aggregation, or whatever). Generally speaking, if whatever you’re trying to make distinct is …

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From stackoverflow.com

7. What’s the Difference Between UNIQUE and DISTINCT in SQL …

May 20, 2021 · Let’s find out what is so different about them and how we can use them in SQL. Despite the words unique and distinct being synonyms, they cover very different things in SQL. The UNIQUE keyword in SQL plays the role of a database constraint; it ensures there are no duplicate values stored in a particular column or a set of columns. On the other hand, the …

From learnsql.com

8. sql server – When to use DISTINCT – Database …

May 27, 2016 · SELECT DISTINCT is sometimes an indication that someone has ‘fixed’ a query that returns duplicate rows in a naive way. This (mis-)use is probably more common among those with relatively little database experience. That said, some people (Chris Date, for example) argue that DISTINCT should be the default qualifier for SELECT; we should have to …

From dba.stackexchange.com

9. T-SQL – DISTINCT Clause – Tutorialspoint

The MS SQL Server DISTINCT keyword is used in conjunction with SELECT statement to eliminate all the duplicate records and fetching only unique records. There may be a situation when you have multiple duplicate records in a table.

From www.tutorialspoint.com


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