What does SELECT distinct mean?

The SELECT DISTINCT statement is used to return only distinct (different) values. Inside a table, a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values.

How does SELECT distinct work?

A SELECT DISTINCT statement first builds our overall result set with all records, i.e including duplicate values based on FROM, JOIN, WHERE, HAVING, etc statements. Next, it sorts the result set based on the column_name or field with which DISTINCT has been used.

Why you shouldn’t use SELECT distinct?

As a general rule, SELECT DISTINCT incurs a fair amount of overhead for the query. Hence, you should avoid it or use it sparingly. The idea of generating duplicate rows using JOIN just to remove them with SELECT DISTINCT is rather reminiscent of Sisyphus pushing a rock up a hill, only to have it roll back down again.

How do you SELECT distinct records?

SQL SELECT DISTINCT Explanation SELECT DISTINCT returns only unique (i.e. distinct) values. SELECT DISTINCT eliminates duplicate values from the results. DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc. DISTINCT operates on a single column.

How can I get distinct values in SQL without distinct?

Below are alternate solutions :

  1. Remove Duplicates Using Row_Number. WITH CTE (Col1, Col2, Col3, DuplicateCount) AS ( SELECT Col1, Col2, Col3, ROW_NUMBER() OVER(PARTITION BY Col1, Col2, Col3 ORDER BY Col1) AS DuplicateCount FROM MyTable ) SELECT * from CTE Where DuplicateCount = 1.
  2. Remove Duplicates using group By.

Does select distinct slow down a query?

Very few queries may perform faster in SELECT DISTINCT mode, and very few will perform slower (but not significantly slower) in SELECT DISTINCT mode but for the later case it is likely that the application may need to examine the duplicate cases, which shifts the performance and complexity burden to the application.

Does select distinct * work?

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.

How do you SELECT unique records from a table without using distinct?

How do you SELECT distinct records based on one column?

“sql select unique rows based on a column” Code Answer’s

  1. DISTINCT.
  2. – select distinct * from employees; ==>
  3. retrieves any row if it has at.
  4. least a single unique column.
  5. ​
  6. – select distinct first_name from employees; ==>
  7. retrieves unique names.
  8. from table. ( removes duplicates)

How do you select distinct in Excel?

To select distinct or unique values without column headers, filter unique values, select the first cell with data, and press Ctrl + Shift + End to extend the selection to the last cell. Tip. In some rare cases, mostly on very large workbooks, the above shortcuts may select both visible and invisible cells.

How do I use distinct in SQL query?

Using SQL DISTINCT. The SQL Distinct command can be used in the SELECT statement to ensure that the query returns only distinct (unique) rows. When the query is selecting the rows it discards any row which is a duplicate of any other row already selected by the query.

What is an example of distinct?

The definition of distinct is separate from or different from. An example of distinct is an identity separate from that of your twin. YourDictionary definition and usage example.

What is a distinct query?

DISTINCT is a keyword in SQL that allows you to show unique or distinct results. It’s added to a SELECT query to eliminate duplicates in the data it displays because columns often contain duplicate values and sometimes you may only want to show unique or distinct values. If you want to actually remove duplicate records,…

By Popular articles