How do I use distinct in one column in SQL?

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 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 I get a single column in SQL?

The SQL SELECT Statement

  1. SELECT column1, column2, FROM table_name;
  2. SELECT * FROM table_name;
  3. Example. SELECT CustomerName, City FROM Customers;
  4. Example. SELECT * FROM Customers;

What is distinct on in SQL?

DISTINCT ON ( expression [.] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. […] Note that the “first row” of each set is unpredictable unless ORDER BY is used to ensure that the desired row appears first.

What is the syntax for single column indexes?

What is the syntax for Single-Column Indexes? Explanation: The basic syntax is as follows : CREATE INDEX index_name ON table_name (column_name); 15. Which of the following index are automatically created by the database server when an object is created?

Is GROUP BY better than distinct?

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.

How do I get only distinct records in SQL?

The SQL SELECT DISTINCT Statement 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.

Does SQL distinct apply to all columns?

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