Click here to Skip to main content
15,885,435 members
Home / Discussions / Database
   

Database

 
GeneralRe: Loading Data on Demand Pin
Eddy Vluggen1-Jun-17 0:35
professionalEddy Vluggen1-Jun-17 0:35 
AnswerRe: Loading Data on Demand Pin
Jörgen Andersson31-May-17 22:18
professionalJörgen Andersson31-May-17 22:18 
GeneralRe: Loading Data on Demand Pin
Richard Andrew x6416-Jun-17 11:20
professionalRichard Andrew x6416-Jun-17 11:20 
QuestionSQL server: How to get backup file information using SMO Pin
w1424326-May-17 17:52
w1424326-May-17 17:52 
AnswerRe: SQL server: How to get backup file information using SMO Pin
Eddy Vluggen2-Jun-17 1:44
professionalEddy Vluggen2-Jun-17 1:44 
QuestionHow to create SQL Server backup folder Pin
w1424326-May-17 17:44
w1424326-May-17 17:44 
QuestionSSRS - dynamic columns depending on client parameter Pin
Danpeking24-May-17 23:33
Danpeking24-May-17 23:33 
QuestionSql server: create table with column that support unique and multiple nulls Pin
w1424323-May-17 20:03
w1424323-May-17 20:03 
SQL server 2014/16.

Want create a table. The table has some columns that need support:
1.Can contain multiple nulls.
2.If not null, then must be unique.
3.The columns has no relationship.
4.Not entire row is unique. Each column is unique.

How to make the CREATE TABLE command?

It seems SQL server can only support one null when using UNIQUE.

Below example is what I wanted:
CREATE TABLE UniqueTest (
col1 int,
col2 int unique null
);

INSERT INTO UniqueTest VALUES (1, 1);
-- SUCCESS

INSERT INTO UniqueTest VALUES (2, 2);
-- SUCCESS

INSERT INTO UniqueTest VALUES (3, 2);
-- FAIL

INSERT INTO UniqueTest VALUES (4, NULL);
-- SUCCESS

INSERT INTO UniqueTest VALUES (5, NULL);
-- SUCCESS


I had searched internet, lots of articles are discussed in old SQL server version, e.g. 2005/2008.
I think the SQL server 2014/2016 has a new CREATE TABLE option to meet my requirement, but I don't know.


The solution from internet would be:
create index on specific column.

But:
1.My table will has 10~30 columns that need unique and nulls. If each column create an index, then will be 10~30 indexes in a table. Is it possible?
2.Lots indexes will lower efficiency. Is it?

AnswerRe: Sql server: create table with column that support unique and multiple nulls Pin
Maciej Los23-May-17 20:27
mveMaciej Los23-May-17 20:27 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
w1424323-May-17 20:45
w1424323-May-17 20:45 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
Richard Deeming24-May-17 8:22
mveRichard Deeming24-May-17 8:22 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
w1424324-May-17 17:32
w1424324-May-17 17:32 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
Richard Deeming25-May-17 0:51
mveRichard Deeming25-May-17 0:51 
AnswerRe: Sql server: create table with column that support unique and multiple nulls Pin
ZurdoDev24-May-17 3:15
professionalZurdoDev24-May-17 3:15 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
Richard Deeming24-May-17 8:19
mveRichard Deeming24-May-17 8:19 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
ZurdoDev24-May-17 8:24
professionalZurdoDev24-May-17 8:24 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
w1424324-May-17 17:45
w1424324-May-17 17:45 
GeneralRe: Sql server: create table with column that support unique and multiple nulls Pin
ZurdoDev25-May-17 0:49
professionalZurdoDev25-May-17 0:49 
QuestionDisplay data only from search parameters Pin
rattlerrFx23-May-17 7:16
rattlerrFx23-May-17 7:16 
QuestionRe: Display data only from search parameters Pin
CHill6023-May-17 10:52
mveCHill6023-May-17 10:52 
AnswerRe: Display data only from search parameters Pin
rattlerrFx23-May-17 13:21
rattlerrFx23-May-17 13:21 
GeneralRe: Display data only from search parameters Pin
CHill6024-May-17 1:06
mveCHill6024-May-17 1:06 
QuestionTeam Please help on the below request Pin
ganesh_naganna23-May-17 0:55
ganesh_naganna23-May-17 0:55 
AnswerRe: Team Please help on the below request Pin
Mycroft Holmes23-May-17 14:55
professionalMycroft Holmes23-May-17 14:55 
QuestionSQL for dynamic mappings Pin
Danpeking22-May-17 3:13
Danpeking22-May-17 3:13 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.