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Today, I will talk to you about how to modify the table structure in SQLServer. Many people may not know much about it. In order to make you understand better, the editor has summarized the following contents for you. I hope you can get something according to this article.

What is the code for beginners to modify the table structure in SQLServer?

①: change field type length

ALTERTABLE table name

Length of ALTERCOLUMN field name type-- varchar (50)

Example: change the original length of the city field of the city table from 20 to 30

ALTERTABLEcity

ALTERCOLUMNcnamevarchar (30)

②: changing field typ

ALTERTABLE table name

Type after the ALTERCOLUMN field name has been changed

Example: change the city name field in the city table from varchar type to int

ALTERTABLEcity

ALTERCOLUMNcnameint

③: adding notnull constraint

ALTERTABLE table name

ALTERCOLUMN field name field type NOTNULL

Example: cid (city number) cannot be entered into a null value

ALTERTABLEcity

ALTERCOLUMNcidintNOTNULL

What is the code for beginners to modify the table structure in SQLServer?

④: setting primary key

ALTERTABLE table name

ADDCONSTRAINT primary key name PRIMARYKEY (field name)

Example: set cid (city number) as the primary key

ALTERTABLEcity

ADDCONSTRAINTPK_cidPRIMARYKEY (cid)

⑤: add field name

ALTERTABLE table name

ADD field name field type DEFAULTNULL

Example: add a pic field to the city table

ALTERTABLEcity

ADDpicvarchar (60) DEFAULTNULL

⑥: changing field name

A.MySQL:

ALTERTABLE table name CHANGE original field name new field name field type

B.Oracle:

ALTERTABLE table name

RENAMECOLUMN original field name TO new field name

C.SQLServer:

EXECsp_rename' table name. Field name', 'changed field name', 'COLUMN'

After reading the above, do you have any further understanding of how to modify the table structure in SQLServer? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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