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How can I do an UPDATE statement with JOIN in SQL Server, based on an Id match?

How can I do an UPDATE statement with JOIN in SQL Server, based on an Id match?

Richard C.

The ProblemJump To Solution

In SQL Server, how do you update rows in one table with data from rows in another? You might want to join two tables in your update, where one table contains more recent or authoritative data than the other. The tables often share an Id or some type of account number that you can match your records against.

Assume you have two tables. One called Person that is kept up to date with correct details. The other table is called PersonArchive and is updated monthly with recent details from Person.

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CREATE TABLE Person ( Id INT PRIMARY KEY, Name VARCHAR(255) ); CREATE TABLE PersonArchive ( Id INT PRIMARY KEY, Name VARCHAR(255) ); INSERT INTO Person(Id, Name) VALUES (1, 'Amir'), (2, 'Sofia'), (3, 'Aya'), (4, 'Mateo'), (5, 'Leila'), (6, 'Yara'), (7, 'Ndidi'), (8, 'Santiago'); INSERT INTO PersonArchive(Id, Name) VALUES (1, 'Abir'), (2, 'Sofya'), (3, 'Aya'), (4, 'Mateo'), (5, 'Leila'), (6, 'Yara'), (7, 'Ndidi'), (8, 'Santiago');

The Solution

Below is an update query that uses a join to update the archive table from the reference table:

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UPDATE old SET old.Name = new.Name FROM PersonArchive old JOIN Person new ON old.id = new.id;

To make the query more readable you could use a WHERE clause instead of a join:

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UPDATE old SET old.Name = new.Name FROM PersonArchive old, Person new WHERE old.id = new.id;

The queries above are likely to be fast. However, they will work only in SQL Server. Each database server’s update syntax is slightly different.

Instead, you can update your table using a subquery, which will work in all database servers, but might run more slowly on large tables:

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UPDATE PersonArchive SET Name = ( SELECT Name FROM Person WHERE PersonArchive.Id = Person.Id );
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