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This article introduces the relevant knowledge of "how Oracle and SQLServer deal with Update sentences". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

In database operations, we often use update statements to modify, update, and so on. However, different databases may also have different processes for handling Update statements.

What should Oracle and SQLServer do with Update statements?

Oracle and SQLServer handle Update statements differently. The results of the same writing will be different, if you are used to using Oracle, you need to pay attention. In complex Update statements, Oracle is generally implemented by subqueries. For example:

Updatetable1t1setc1= (selectt2.c1fromtable2t2wheret1.c2=t2.c2)

Of course, simply copying the statement to run in sqlserver will prompt a syntax error:

As soon as a syntax error occurs in the line

What should Oracle and SQLServer do with Update statements?

At this point, you may think that since aliases are not supported, just use the table name and modify the statement as follows:

Updatetable1setc1= (selectt2.c1fromtable2t2wheretable1.c2=t2.c2)

This statement does work in sqlserver, and if you do run it, you will be miserable. Because all the records in table1 have been updated, and some of the records that do not need to be updated have been updated to null, instead of updating only records that conform to subqueries as in oracle. How do you update this situation in sqlserver? The answer is updatefrom.

To handle this situation normally in sqlserver, you need to modify the above sql statement. The modified sql is as follows:

Updatetable1setc1=t2.c2fromtable2t2wherec2=t2.c1

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