How use distinct and top in SQL?

How use distinct and top in SQL?

SELECT DISTINCT TOP 2 name FROM [ATTENDANCE] ; In the above query, name is the column_name and [ATTENDANCE] is the table_name. You can also use WHERE with this to make filtering conditions. You can use GROUP BY instead of DISTINCT, and you can use OUTER APPLY with TOP(1) to fetch only one matching result.

How do you select top distinct?

To do so, select Query -> Include Actual Query Plan from the menu before executing the query. The “Stream Aggregate” icon is for the DISTINCT operation and “Top” for the TOP 10 one. It may seem somewhat counterintuitive to see DISTINCT listed first within the SELECT statement.

How can I get unique values from a column with repeated values 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 distinct have to be first?

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.

Why we should not use distinct in SQL?

The fact that the resultset has duplicates is frequently (though not always) the result of a poor database design, an ineffective query, or both. In any case, issuing the query without the DISTINCT keyword yields more rows than expected or needed so the keyword is employed to limit what is returned to the user.

How do I select distinct rows in MySQL?

The go to solution for removing duplicate rows from your result sets is to include the distinct keyword in your select statement. It tells the query engine to remove duplicates to produce a result set in which every row is unique. The group by clause can also be used to remove duplicates.

Can we use distinct with top?

How do you SELECT distinct values in an Access query?

Answer: Open your query in design view. Right-click somewhere in the Query window beside a table (but not on a table) and select Properties from the popup menu. Set the “Unique Values” property to Yes.

Will distinct return NULL values?

COUNT DISTINCT does not count NULL as a distinct value. COUNT(DISTINCT BY(col2) col1) counts col1 values for distinct col2 values; however, the distinct col2 values may include a single NULL as a distinct value.

How does select distinct check for duplicates in SQL?

Will be greatfull for any kind of help. There are multiple columns in the select query, the query check for uniqueness across all the columns, not just the one in brackets. The SQL DISTINCT keyword is used in conjunction with SELECT statement to eliminate all the duplicate records and fetching only unique records..

How to eliminate duplicates in a SELECT statement?

To eliminate the duplicates, you use the DISTINCT operator as follows: Notice you can use the DISTINCT operator in the SELECT statement only. The SELECT statement uses the values of the columns specified after the DISTINCT operator for evaluating the uniqueness of the rows in the result set.

How to SELECT DISTINCT values from query results in?

You can use DISTINCT ON to display the first of each value in “col1”: There are a few scenarios where distinct keyword cannot be used. 1. DISTINCT is a reserved keyword in PostgreSQL, so we cannot specify it as an object name. 2. In a SELECT query we cannot have more than one DISTINCT keyword:

When to use distinct or all in SQL?

Unlike the DISTINCT operator, the ALL operator includes all rows that contain duplicate values. The following queries return the same result set. The SELECT statement uses the ALL operator by default.