How use top clause with distinct in SQL?


  1. TOP Clause: …
  2. Note: If you don’t have database to test then see my previous article. …
  4. Syntax description: …
  5. Examples of SELECT TOP statement: …
  6. Output:
  7. TOP to return PERCENT of ROWS. …
  8. Output:

What is distinct top in SQL?

If you have multiple columns then all those columns combined make up one distinct record. SELECT distinct TOP 10 personID FROM TableA. Note that without an ORDER BY this will return the first 10 records in no particular order. The results could be different each time you run the query.

How do I select top 10 records in SQL Server?

Example – Using TOP PERCENT keyword SELECT TOP(10) PERCENT employee_id, last_name, first_name FROM employees WHERE last_name = ‘Anderson’ ORDER BY employee_id; This SQL Server SELECT TOP example would select the first 10% of the records from the full result set.

How do I use distinct in one column in SQL?

Adding the DISTINCT keyword to a SELECT query causes it to return only unique values for the specified column list so that duplicate rows are removed from the result set. Since DISTINCT operates on all of the fields in SELECT’s column list, it can’t be applied to an individual field that are part of a larger group.

How do you select unique records from a table?

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.

What does the distinct keyword do when it is used in a select clause?

Distinct command in SQL is used along with the Select command in order to retrieve only distinct or dissimilar values from a table. It is mainly used as a method to filter duplicate records and fetch only unique records from a given table, where there is a possibility of fields having multiple duplicate records.

What is the difference between distinct and unique in SQL?

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.

Does distinct apply to all columns?

Yes, DISTINCT works on all combinations of column values for all columns in the SELECT clause.

How do you select distinct values for multiple columns in SQL?

DISTINCT on multiple columns

  1. Sample Select statement.
  2. Select with distinct on two columns.
  3. Select with distinct on three columns.
  4. Select with distinct on all columns of the first query.
  5. Select with distinct on multiple columns and order by clause.
  6. Count() function and select with distinct on multiple columns.

How do you select the top 5 values in SQL?


  1. SQL Server / MS Access Syntax. SELECT TOP numberpercent column_name(s) FROM table_name;
  2. MySQL Syntax. SELECT column_name(s) FROM table_name. LIMIT number;
  3. Example. SELECT * FROM Persons. LIMIT 5;
  4. Oracle Syntax. SELECT column_name(s) FROM table_name. WHERE ROWNUM <= number;
  5. Example. SELECT * FROM Persons.

How do I get top 10 records in SQL Developer?

Returning TOP N Records

  1. Microsoft SQL Server SELECT TOP 10 column FROM table.
  2. PostgreSQL and MySQL SELECT column FROM table LIMIT 10.
  3. Oracle SELECT column FROM table WHERE ROWNUM <= 10.
  4. Sybase SET rowcount 10 SELECT column FROM table.
  5. Firebird SELECT FIRST 10 column FROM table.

How do you select top 1 record in each group in SQL?

[InventoryAllocations] ORDER BY ROW_NUMBER() OVER(PARTITION BY DocumentID ORDER BY [RecordTimeStamp] DESC); TOP 1 works with WITH TIES here. WITH TIES means that when ORDER BY = 1 , then SELECT takes this record (because of TOP 1 ) and all others that have ORDER BY = 1 (because of WITH TIES ).

How do I select a single value in SQL?

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. The query uses the combination of values in all specified columns in the SELECT list to evaluate the uniqueness.

How do you use distinct in the middle of a selected statement?

2 Answers. The DISTINCT clause filters out FULL DUPLICATE ROWS. It goes right after the SELECT keyword, since it applies to the entire row, not single columns. You cannot use it in between columns.

How do I count distinct values in SQL?

SELECT COUNT (DISTINCT item_num) FROM items; If the COUNT DISTINCT function encounters NULL values, it ignores them unless every value in the specified column is NULL. If every column value is NULL, the COUNT DISTINCT function returns zero (0).

How can I get unique records without using distinct in SQL?

SQL Remove Duplicates without Distinct

  1. Remove Duplicates Using Row_Number. …
  2. 2.Remove Duplicates using self Join. …
  3. Remove Duplicates using group By.

How can I select unique records from a table in MySQL?

You can use the DISTINCT command along with the SELECT statement to find out unique records available in a table. mysql> SELECT DISTINCT last_name, first_name -> FROM person_tbl -> ORDER BY last_name; An alternative to the DISTINCT command is to add a GROUP BY clause that names the columns you are selecting.

How do I select non distinct rows in SQL?

  1. select count(distinct NAME) from MYTABLE.

Is it good to use distinct in SQL?

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.

Why do we use distinct in SQL?

The distinct keyword is used in conjunction with select keyword. It is helpful when there is a need of avoiding duplicate values present in any specific columns/table. When we use distinct keyword only the unique values are fetched.

Should I use 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.

What is the difference between SELECT and SELECT distinct?

The SELECT clause of a query statement can include two optional keywords — ALL or DISTINCT, followed by the projection-list . If the ALL keyword is specified, duplicate rows are not removed from the query result. If the DISTINCT option is specified, all duplicate rows of data values are excluded from the query result.

Is distinct or GROUP BY better?

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.

Is GROUP BY better than distinct?

If you want to group your results, use GROUP BY, if you just want a unique list of a specific column, use DISTINCT.

Can we use distinct and group by together in SQL?

  • You can use it together in SELECT …, COUNT(DISTINCT …) …
  • no, you can drop the DISTINCT , it’s redundant. …
  • group by delivers distinct results. …
  • A few weeks back, I was browsing through some articles and came across some discussion about some special use-case for this.

Can we use distinct in 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.

What can SQL not do?

The SQL NOT condition (sometimes called the NOT Operator) is used to negate a condition in the WHERE clause of a SELECT, INSERT, UPDATE, or DELETE statement.

How do I SELECT all columns except one in SQL?

Just right click on the table > Script table as > Select to > New Query window. You will see the select query. Just take out the column you want to exclude and you have your preferred select query. …

  1. get all columns.
  2. loop through all columns and remove wich you want.
  3. make your query.