Access database uses SQL statement to add fields, modify fields, and delete fields

Here is an example:
Create a table using DDL's Create Table 1, the primary key is the automatically numbered field, and the other field is a text field with length 10.

Copy the codeThe code is as follows:

CREATE TABLE Table1 (Id COUNTER CONSTRAINT PrimaryKey PRIMARY KEY, MyText TEXT (10)) 

Create another table with two fields Table2, field id is a long integer, field MyText is text

Copy the codeThe code is as follows:

CREATE TABLE Table2 (Id LONG, MyText TEXT)

Use the following statement to establish a one-to-many relationship between Table1 and Table2, update cascaded, and delete cascaded:

Copy the codeThe code is as follows:

ALTER TABLE Table2 ADD CONSTRAINT Relation1 FOREIGN KEY ([Id]) REFERENCES Table1 ([Id]) ON UPDATE CASCADE ON DELETE CASCADE 

Use the following statement to delete a relationship:

Copy the codeThe code is as follows:

ALTER TABLE Table2 DROP CONSTRAINT Relation1

Delete Table1 with the following statement:

Copy the codeThe code is as follows:

DROP TABLE Table1

Set a field as the primary key

Copy the codeThe code is as follows:

ALTER TABLE Table 1 ALTER COLUMN [id] COUNTER CONSTRAINT MyPrimaryKey PRIMARY KEY

Add a field MySalary

Copy the codeThe code is as follows:

alter table AAA add COLUMN MySalary CURRENCY

Delete a field MySalary

Copy the codeThe code is as follows:

alter table AAA drop COLUMN MySalary