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This article will explain in detail how to modify the table structure in Oracle. 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.

1. Modify the data type of a field

Syntax: ALTER TABLE table name MODIFY (column name data type); eg1: when you modify the length of a column, you can only edit it larger than the actual length of the existing field, otherwise it prompts the following error: ORA-01441: column length cannot be reduced because some values are too large

two。 Increase by one column

Syntax: ALTER TABLE table name ADD (column name data type); eg1:ALTER TABLE emp ADD (column1 NUMBER (38Power0) not null)

3. Change the list

Syntax: ALTER TABLE table name RENAME COLUMN after column name TO new column name; eg1:ALTER TABLE emp RENAME COLUMN column1 TO column2

One truth every day

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4. Delete a column

Syntax: ALTER TABLE table name DROP COLUMN column name; eg1:alter table emp drop column column1

5. Change the table name

Syntax: table name after ALTER TABLE RENAME TO new table name; eg1:alter table emp rename to emp_new

6. Add comments to the table

Comment column on table name. Column name is' comment content'; / modify the comment content of the column of the table comment on table emp.column1 IS 'comment content'; / / modify the comments of the table on how to modify the table structure in Oracle is shared here, I hope the above content can be of some help to you, 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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