Insert unique in SQL

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Hello,

I have SQL server Database table with more than 30 million records, what is the best way to insert unique values to this table

Any suggestions.

What I have tried:

I tried:

if not exists (select * from MyTable where Name = @Name and ... )
begin
insert into MyTable (Name,...) values (@Name,...)
end

But that is taking lots of time to execute

I created an index to every column im checking if its exist

Posted 15-Jul-16 0:57am

Hidhoud1991

Updated 15-Jul-16 3:19am

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[no name] 15-Jul-16 6:59am

Why not _one_ unique index over the columns you have in the "where" clause?

Hidhoud1991 15-Jul-16 7:37am

they will exceed the 900 byte allowed for index size

[no name] 15-Jul-16 7:46am

I understand. Maybe this will give you an idea, but I assume you know it allready: Living with SQL’s 900 Byte Index Key Length Limit – Bart Duncan's SQL Weblog[^]

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Vignesh Mani · Accepted Answer · 2016-07-15T03:19:00

I think You need to insert one table data to another table.

SQL

INSERT INTO destTable
SELECT Field1,Field2,Field3,... 
FROM srcTable
WHERE NOT EXISTS(SELECT * 
                 FROM destTable 
                 WHERE (srcTable.Field1=destTable.Field1 and
                       SrcTable.Field2=DestTable.Field2...etc.)
                 )

SQL

insert into test.t2(name2) 
select distinct name1 from test.t1 t1 where NOT EXISTS(select name2 from test.t2 t2 where t1.name1=t2.name2);