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This article will explain in detail how to implement the modification operation in the SQL database. The content of the article is of high quality, so the editor will share it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

What is the modification operation method in SQL database? Although we would think that inserting and deleting tuples are "modifications" to the database, the modification in the SQ L database is a very specific change to the database: some of the components of one or more tuples that already exist in the database have changed. The general format of the modification statement is:

1. Keyword UPDATE

two。 Relationship name, such as R

3. Keyword SET

4. A series of formulas, each of which sets an attribute of relation R to the value of an expression or constant

5. Keyword WHERE, and

6. Conditions.

That is, the modified format is UPDATERSET < New assignment > WHERE < condition >; each new assignment (item 4 above) consists of attributes, equal signs, and formulas. If there are multiple assignments, separate them with a comma. First of all, the function of this statement is to find all the tuples that satisfy condition 6 in the relation R, and then by evaluating the formula in 4 and assigning the tuple components corresponding to the corresponding attributes in the relation R. as a result, each tuple that meets the condition is changed.

On how to achieve modification operations in the SQL database to share here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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