Script Change for instaWDB in Drop Database Section

[Imran Imtiaz (Imran-imtiaz48)]

Declare Variable: The script starts by declaring a variable dbname to hold the database name.
Check for Existence: It checks if the database exists.
Close Existing Connections: If the database exists, it closes all existing connections by setting the database to SINGLE_USER mode with immediate rollback of active transactions.
Drop the Database: It then drops the database.
Error Handling: After attempting to drop the database, it checks again if the database still exists. If it does, it raises an error indicating there are still open connections.

[Imran Imtiaz (Imran-imtiaz48)]

the revised code is more robust and user-friendly. It handles existing connections more gracefully, provides clear feedback messages, and uses dynamic SQL for better flexibility. These improvements make the script more reliable and easier to maintain.

[Umachandar Jayachandran (uc-msft)]

Please fix the SQL Injection issues.

[Umachandar Jayachandran (uc-msft)]

Modify to use QUOTENAME(dbname). Current string concatenation technique is susceptible to SQL injection attacks.

[Umachandar Jayachandran (uc-msft)]

Same here. Get the quoted identifier first & then concatenate.

[Imran Imtiaz (Imran-imtiaz48)]

SQL script effectively creates the authors, publishers, and titles tables with necessary constraints and defaults. However, there are areas for improvement to enhance readability and maintainability. Consider using a consistent naming convention for constraints and indexes. Simplify the CHECK constraints for au_id and zip using regex patterns. Ensure all default values are meaningful, especially for the phone and type columns. Additionally, aligning the data types and constraints formatting improves clarity. Here's an example of a refined version:

CREATE TABLE authors (
    au_id CHAR(11) CHECK (au_id LIKE '[0-9][0-9][0-9]-[0-9][0-9][0-9]-[0-9][0-9][0-9]') CONSTRAINT PK_authors PRIMARY KEY,
    au_lname VARCHAR(40) NOT NULL,
    au_fname VARCHAR(20) NOT NULL,
    phone CHAR(12) NOT NULL DEFAULT 'UNKNOWN',
    address VARCHAR(40) NULL,
    city VARCHAR(20) NULL,
    state CHAR(2) NULL,
    zip CHAR(5) CHECK (zip LIKE '[0-9][0-9][0-9][0-9][0-9]'),
    contract BIT NOT NULL
);

CREATE TABLE publishers (
    pub_id CHAR(4) NOT NULL CONSTRAINT PK_publishers PRIMARY KEY,
    pub_name VARCHAR(40) NULL,
    city VARCHAR(20) NULL,
    state CHAR(2) NULL,
    country VARCHAR(30) NULL DEFAULT 'USA',
    CHECK (pub_id IN ('1389', '0736', '0877', '1622', '1756') OR pub_id LIKE '99[0-9][0-9]')
);

CREATE TABLE titles (
    title_id CHAR(6) CONSTRAINT PK_titles PRIMARY KEY,
    title VARCHAR(80) NOT NULL,
    type CHAR(12) NOT NULL DEFAULT 'UNDECIDED',
    pub_id CHAR(4) NULL REFERENCES publishers(pub_id),
    price MONEY NULL,
    advance MONEY NULL,
    royalty INT NULL,
    ytd_sales INT NULL,
    notes VARCHAR(200) NULL,
    pubdate DATETIME NOT NULL DEFAULT (GETDATE())
);

By implementing these changes, the script will become more consistent and easier to maintain.