COUNT, DISTINCT, and NULLs in SQL Server

preview_player
Показать описание
NULLs are interesting values. While they fill an important need in the database, it's not always intuitive how different SQL Server statements and functions handle them.

This week we examine how COUNTs and DISTINCTs interact with NULLs...and how they may not always be doing what you expect with them.

Related blog post with more examples:

Follow me on Twitter:
  1. Bert Wagner
  2. SQL Server
  3. SQL
  4. SQL training
  5. SQL tutorial
  6. null
Рекомендации по теме
COUNT, DISTINCT, and 0:03:25

COUNT, DISTINCT, and NULLs in SQL Server

How to get 0:00:27

How to get COUNT of DISTINCT VALUES in SQL

SQL : Fastest 0:01:29

SQL : Fastest Way to Count Distinct Values in a Column, Including NULL Values

How to Use 0:02:21

How to Use COUNT, COUNT(*), and COUNT(DISTINCT) in SQL – A Beginner's Guide

SQL : Count 0:01:11

SQL : Count distinct and Null value is eliminated by an aggregate

Count Function in 0:11:53

Count Function in SQL | Count_BIG() | Count(DISTINCT Col)| WHILE Loop in SQL | ASNI NULL Warning

How to Count 0:02:51

How to Count Distinct Installations for Each Member in SQL

SQL | Count(*) 0:00:24

SQL | Count(*) vs Count(1) Vs Count(colname) #sqltips

SQL|Comparing COUNT(*)-COUNT(1)-COUNT('a')-COUNT(col_nm)-COUNT(DISTINCT col_nm)|Common 0:06:45

SQL|Comparing COUNT(*)-COUNT(1)-COUNT('a')-COUNT(col_nm)-COUNT(DISTINCT col_nm)|Common SQL...

SQL : Count 0:01:07

SQL : Count distinct values in MySQL without folding NULL values

SQL : Why 0:01:09

SQL : Why does count( distinct ) with NULL columns return 0 in Hive SQL?

SQL | What's 0:00:24

SQL | What's wrong with this SQL Query ? Count Distinct #sqltips

Counting null and 0:00:33

Counting null and non-null values in SQL SERVER | Part 9 #sqlserver #coding #dataqueries

Using DISTINCT in 0:08:53

Using DISTINCT in SQL

SQL Counting NULLS 0:03:37

SQL Counting NULLS

How to using 0:03:33

How to using DISTINCT and NULL to SELECT Multiple Table in SQL SERVER with Transact SQL (T-SQL)

SQL : Count 0:01:09

SQL : Count number of NULL values in each column in SQL

SQL : TSQL 0:01:22

SQL : TSQL Count function and distinct missing NULL values

Aggregate Functions in 0:06:25

Aggregate Functions in SQL SERVER | COUNT(*) VS COUNT(DISTINCT)

SQL, Count function 0:02:40

SQL, Count function and null values, 22Ae50

SQL DISTINCT & 0:08:27

SQL DISTINCT & SQL NULL VALUES WITH EXAMPLES USING ORACLE SQL DEVELOPER

8 2 Count 0:07:15

8 2 Count unique values - SQL тестирование

How to Integrate 0:01:29

How to Integrate COUNT(DISTINCT) in SQL Query for MG Items Without Errors

Basics of SQL 0:07:27

Basics of SQL | Select, where, count, distinct, orderby, AND, NOT, OR, NULL

Комментарии
Автор

How about doing the count distinct with a + case when exists (select * from ... where col1 is null) then 1 else 0 end?

Sttuey
Автор

Hola, qué hacer si la extracción de la tabla de la base de datos es en tuplas y estos comandos no funcionan? Hay forma de evitar que las tablas se extraigan en tuplas en sql?

nohemialvarez
Автор

select distinct(email_subject) as cnt_sub
from lemonemails

mercypaul