The specific setting method is as follows:

Rename the old name of the column to the new name.

Alter table table name alter column field name varchar(255) not null.

Change table name Add field name type is not empty, default value is 0.

The SQL data type of Microsoft Jet database engine consists of 13 basic data types, which are defined by Microsoft Jet database engine and several verified synonyms.

Common ones are: plastic, single precision, double precision, variable-length characters, fixed-length characters, long type, date and so on.

Data type is an attribute of data, indicating the type of information represented by data.

Any computer language defines its own data type. Of course, different programming languages have different characteristics, and the types and names of defined data types are more or less different.