SQL from zero to quick mastery of "basic statement"

1. Using the T-SQL statement to create the data table authors, enter the following statement.

CREATE TABLE Authors

{

auth_id int PRIMARY key,--data table primary key

Auth_name VARCHAR () not null unique,--author name, cannot be empty

Auth_gender tinyint not NULL DEFAULT (1)--author Sex: male (1), female (0)

};

2. Add a new field with the name Auth_note in the Authors table, the field data type is varchar (100), the null value is allowed, and the input statement is as follows.

ALTER TABLE Authors

ADD auth_note VARCHAR (+) NULL

3. In the authors table, modify the field named Auth_phone, change the data type to varchar (15), and enter the following statement.

ALTER TABLE Authors

ALTER COLUMN Auth_phone VARCHAR (15)

GO

4. Delete the Auth_phone field in the Authors table and enter the following statement.

ALTER TABE Authors

DROP COLUMN Auth_phone

5. Define the table table_emp and set the e_id field in the table as the primary key column, and enter the following statement.

CREATE TABLE Table_emp

(

e_id CHAR (PRIMARY KEY),

E_name VARCHAR (+) not NULL,

E_deptid INT,

E_phone VARCHAR (CONSTRAINT) Uq_phone UNIQUE

);

6. Delete the primary KEY constraints and uniqueness constraints in the member table, and the T-SQL statements are as follows.

ALTER TABLE Member

DROP CONSTRAINT Pk_member,uq_firstname

7. Delete the authors table from the test database and enter the following statement.

Use Test

GO

DROP TABLE Authors

SQL from zero to quick mastery of "basic statement"