Tukukkk

In SQL Server 2008 (or better), use MERGE

MERGE INTO YourTable T

   USING other_table S 

      ON T.id = S.id

         AND S.tsql = 'cool'

WHEN MATCHED THEN

   UPDATE 

      SET col1 = S.col1, 

          col2 = S.col2;

Alternatively:

MERGE INTO YourTable T

   USING (

          SELECT id, col1, col2 

            FROM other_table 

           WHERE tsql = 'cool'

         ) S

      ON T.id = S.id

WHEN MATCHED THEN

   UPDATE 

      SET col1 = S.col1, 

          col2 = S.col2;

UPDATE table 

SET Col1 = i.Col1, 

    Col2 = i.Col2 

FROM (

    SELECT ID, Col1, Col2 

    FROM other_table) i

WHERE 

    i.ID = table.ID

I'd modify Robin's excellent answer to the following:

UPDATE Table

SET Table.col1 = other_table.col1,

 Table.col2 = other_table.col2

FROM

    Table

INNER JOIN other_table ON Table.id = other_table.id

WHERE

    Table.col1 != other_table.col1

OR Table.col2 != other_table.col2

OR (

    other_table.col1 IS NOT NULL

    AND Table.col1 IS NULL

)

OR (

    other_table.col2 IS NOT NULL

    AND Table.col2 IS NULL

)

Without a WHERE clause, you'll affect even rows that don't need to be affected, which could (possibly) cause index recalculation or fire triggers that really shouldn't have been fired.

One way

UPDATE t 

SET t.col1 = o.col1, 

    t.col2 = o.col2

FROM 

    other_table o 

  JOIN 

    t ON t.id = o.id

WHERE 

    o.sql = 'cool'

Another possibility not mentioned yet is to just chuck the SELECT statement itself into a CTE and then update the CTE.

;WITH CTE

     AS (SELECT T1.Col1,

                T2.Col1 AS _Col1,

                T1.Col2,

                T2.Col2 AS _Col2

         FROM   T1

                JOIN T2

                  ON T1.id = T2.id

         /*Where clause added to exclude rows that are the same in both tables

           Handles NULL values correctly*/

         WHERE EXISTS(SELECT T1.Col1,

                             T1.Col2

                       EXCEPT

                       SELECT T2.Col1,

                              T2.Col2))

UPDATE CTE

SET    Col1 = _Col1,

       Col2 = _Col2

This has the benefit that it is easy to run the SELECT statement on its own first to sanity check the results, but it does requires you to alias the columns as above if they are named the same in source and target tables.

This also has the same limitation as the proprietary UPDATE ... FROM syntax shown in four of the other answers. If the source table is on the many side of a one-to-many join then it is undeterministic which of the possible matching joined records will be used in the Update (an issue that MERGE avoids by raising an error if there is an attempt to update the same row more than once).

For the record (and others searching like I was), you can do it in MySQL like this:

UPDATE first_table, second_table

SET first_table.color = second_table.color

WHERE first_table.id = second_table.foreign_id

Using alias:

UPDATE t

   SET t.col1 = o.col1

  FROM table1 AS t

         INNER JOIN 

       table2 AS o 

         ON t.id = o.id

The simple way to do it is:

UPDATE

    table_to_update,

    table_info

SET

    table_to_update.col1 = table_info.col1,

    table_to_update.col2 = table_info.col2



WHERE

    table_to_update.ID = table_info.ID

This may be a niche reason to perform an update (for example, mainly used in a procedure), or may be obvious to others, but it should also be stated that you can perform an update-select statement without using join (in case the tables you're updating between have no common field).

update

    Table

set

    Table.example = a.value

from

    TableExample a

where

    Table.field = *key value* -- finds the row in Table 

    AND a.field = *key value* -- finds the row in TableExample a

Here is another useful syntax:

UPDATE suppliers

SET supplier_name = (SELECT customers.name

                     FROM customers

                     WHERE customers.customer_id = suppliers.supplier_id)

WHERE EXISTS (SELECT customers.name

              FROM customers

              WHERE customers.customer_id = suppliers.supplier_id);

It checks if it is null or not by using "WHERE EXIST".

I add this only so you can see a quick way to write it so that you can check what will be updated before doing the update.

UPDATE Table 

SET  Table.col1 = other_table.col1,

     Table.col2 = other_table.col2 

--select Table.col1, other_table.col,Table.col2,other_table.col2, *   

FROM     Table 

INNER JOIN     other_table 

    ON     Table.id = other_table.id 

If you use MySQL instead of SQL Server, the syntax is:

UPDATE Table1

INNER JOIN Table2

ON Table1.id = Table2.id

SET Table1.col1 = Table2.col1,

    Table1.col2 = Table2.col2

UPDATE from SELECT with INNER JOIN in SQL Database

Since there are too many replies of this post, which are most heavily up-voted, I thought I would provide my suggestion here too. Although the question is very interesting, I have seen in many forum sites and made a solution using INNER JOIN with screenshots.

At first, I have created a table named with schoolold and inserted few records with respect to their column names and execute it.

Then I executed SELECT command to view inserted records.

Then I created a new table named with schoolnew and similarly executed above actions on it.

Then, to view inserted records in it, I execute SELECT command.

Now, Here I want to make some changes in third and fourth row, to complete this action, I execute UPDATE command with INNER JOIN.

To view the changes I execute the SELECT command.

You can see how Third and Fourth records of table schoolold easily replaced with table schoolnew by using INNER JOIN with UPDATE statement.

And if you wanted to join the table with itself (which won't happen too often):

update t1                    -- just reference table alias here

set t1.somevalue = t2.somevalue

from table1 t1               -- these rows will be the targets

inner join table1 t2         -- these rows will be used as source

on ..................        -- the join clause is whatever suits you

The following example uses a derived table, a SELECT statement after the FROM clause, to return the old and new values for further updates:

UPDATE x

SET    x.col1 = x.newCol1,

       x.col2 = x.newCol2

FROM   (SELECT t.col1,

               t2.col1 AS newCol1,

               t.col2,

               t2.col2 AS newCol2

        FROM   [table] t

               JOIN other_table t2

                 ON t.ID = t2.ID) x

Updating through CTE is more readable than the other answers here:

;WITH cte

     AS (SELECT col1,col2,id

         FROM   other_table

         WHERE  sql = 'cool')

UPDATE A

SET    A.col1 = B.col1,

       A.col2 = B.col2

FROM   table A

       INNER JOIN cte B

               ON A.id = B.id

If you are using SQL Server you can update one table from another without specifying a join and simply link the two from the where clause. This makes a much simpler SQL query:

UPDATE Table1

SET Table1.col1 = Table2.col1,

    Table1.col2 = Table2.col2

FROM

    Table2

WHERE

    Table1.id = Table2.id

The other way is to use a derived table:

UPDATE t

SET t.col1 = a.col1

    ,t.col2 = a.col2

FROM (

SELECT id, col1, col2 FROM @tbl2) a

INNER JOIN @tbl1 t ON t.id = a.id

Sample data

DECLARE @tbl1 TABLE (id INT, col1 VARCHAR(10), col2 VARCHAR(10))

DECLARE @tbl2 TABLE (id INT, col1 VARCHAR(10), col2 VARCHAR(10))



INSERT @tbl1 SELECT 1, 'a', 'b' UNION SELECT 2, 'b', 'c'



INSERT @tbl2 SELECT 1, '1', '2' UNION SELECT 2, '3', '4'



UPDATE t

SET t.col1 = a.col1

    ,t.col2 = a.col2

FROM (

SELECT id, col1, col2 FROM @tbl2) a

INNER JOIN @tbl1 t ON t.id = a.id



SELECT * FROM @tbl1

SELECT * FROM @tbl2

UPDATE TQ

SET TQ.IsProcessed = 1, TQ.TextName = 'bla bla bla'

FROM TableQueue TQ

INNER JOIN TableComment TC ON TC.ID = TQ.TCID

WHERE TQ.IsProcessed = 0

To make sure you are updating what you want, select first

SELECT TQ.IsProcessed, 1 AS NewValue1, TQ.TextName, 'bla bla bla' AS NewValue2

FROM TableQueue TQ

INNER JOIN TableComment TC ON TC.ID = TQ.TCID

WHERE TQ.IsProcessed = 0

Use:

drop table uno

drop table dos



create table uno

(

    uid int,

    col1 char(1),

    col2 char(2)

)

create table dos

(

    did int,

    col1 char(1),

    col2 char(2),

    [sql] char(4)

)

insert into uno(uid) values (1)

insert into uno(uid) values (2)

insert into dos values (1,'a','b',null)

insert into dos values (2,'c','d','cool')



select * from uno 

select * from dos

EITHER:

update uno set col1 = (select col1 from dos where uid = did and [sql]='cool'), 

col2 = (select col2 from dos where uid = did and [sql]='cool')

OR:

update uno set col1=d.col1,col2=d.col2 from uno 

inner join dos d on uid=did where [sql]='cool'



select * from uno 

select * from dos

If the ID column name is the same in both tables then just put the table name before the table to be updated and use an alias for the selected table, i.e.:

update uno set col1 = (select col1 from dos d where uno.[id] = d.[id] and [sql]='cool'),

col2  = (select col2 from dos d where uno.[id] = d.[id] and [sql]='cool')

There is even a shorter method and it might be surprising for you:

Sample data set:

CREATE TABLE #SOURCE ([ID] INT, [Desc] VARCHAR(10));

CREATE TABLE #DEST   ([ID] INT, [Desc] VARCHAR(10));



INSERT INTO #SOURCE VALUES(1,'Desc_1'), (2, 'Desc_2'), (3, 'Desc_3');

INSERT INTO #DEST   VALUES(1,'Desc_4'), (2, 'Desc_5'), (3, 'Desc_6');

Code:

UPDATE #DEST

SET #DEST.[Desc] = #SOURCE.[Desc]

FROM #SOURCE

WHERE #DEST.[ID] = #SOURCE.[ID];

The below solution works for a MySQL database:

UPDATE table1 a , table2 b 

SET a.columname = 'some value' 

WHERE b.columnname IS NULL ;

In the accepted answer, after the:

SET

Table_A.col1 = Table_B.col1,

Table_A.col2 = Table_B.col2

I would add:

OUTPUT deleted.*, inserted.*

What I usually do is putting everything in a roll backed transaction and using the "OUTPUT": in this way I see everything that is about to happen. When I am happy with what I see, I change the ROLLBACK into COMMIT.

I usually need to document what I did, so I use the "results to Text" option when I run the roll-backed query and I save both the script and the result of the OUTPUT. (Of course this is not practical if I changed too many rows)

The other way to update from a select statement:

UPDATE A

SET A.col = A.col,B.col1 = B.col1

FROM  first_Table AS A

INNER JOIN second_Table AS B  ON A.id = B.id WHERE A.col2 = 'cool'

UPDATE table AS a

INNER JOIN table2 AS b

ON a.col1 = b.col1

INNER JOIN ... AS ...

ON ... = ...

SET ...

WHERE ...

Consolidating all the different approaches here.

1. Select update


2. Update with a common table expression


3. Merge

Sample table structure are below and will update from Product_BAK to Product table.

Product

CREATE TABLE [dbo].[Product](

    [Id] [int] IDENTITY(1, 1) NOT NULL,

    [Name] [nvarchar](100) NOT NULL,

    [Description] [nvarchar](100) NULL

) ON [PRIMARY]

Product_BAK

    CREATE TABLE [dbo].[Product_BAK](

        [Id] [int] IDENTITY(1, 1) NOT NULL,

        [Name] [nvarchar](100) NOT NULL,

        [Description] [nvarchar](100) NULL

    ) ON [PRIMARY]

1. Select update

    update P1

    set Name = P2.Name

    from Product P1

    inner join Product_Bak P2 on p1.id = P2.id

    where p1.id = 2

2. Update with a common table expression

    ; With CTE as

    (

        select id, name from Product_Bak where id = 2

    )

    update P

    set Name = P2.name

    from  product P  inner join CTE P2 on P.id = P2.id

    where P2.id = 2

3. Merge

    Merge into product P1

    using Product_Bak P2 on P1.id = P2.id



    when matched then

    update set p1.[description] = p2.[description], p1.name = P2.Name;

In the Merge statement, we can do inset if not finding a matching record in the target, but exist in the source and please find syntax:

    Merge into product P1

    using Product_Bak P2 on P1.id = P2.id;



    when matched then

    update set p1.[description] = p2.[description], p1.name = P2.Name;



    WHEN NOT MATCHED THEN

    insert (name, description)

    values(p2.name, P2.description);

You can use from this for update in sql server

UPDATE

    T1

SET

   T1.col1 = T2.col1,

   T1.col2 = T2.col2

FROM

   Table1 AS T1

INNER JOIN Table2 AS T2

    ON T1.id = T2.id

WHERE

    T1.col3 = 'cool'

declare @tblStudent table (id int,name varchar(300))

declare @tblMarks table (std_id int,std_name varchar(300),subject varchar(50),marks int)



insert into @tblStudent Values (1,'Abdul')

insert into @tblStudent Values(2,'Rahim')



insert into @tblMarks Values(1,'','Math',50)

insert into @tblMarks Values(1,'','History',40)

insert into @tblMarks Values(2,'','Math',30)

insert into @tblMarks Values(2,'','history',80)





select * from @tblMarks



update m

set m.std_name=s.name

 from @tblMarks as m

left join @tblStudent as s on s.id=m.std_id



select * from @tblMarks

like this; but you must sure update table and table after from have be same.

UPDATE Table SET col1, col2

FROM table

inner join other_table Table.id = other_table.id

WHERE sql = 'cool'