Using ANSI SQL

18 Q&A flashcards covering ANSI SQL, vendor lock-in, proprietary extensions, PostgreSQL compliance, key terms (CTE, UUID), ACID, and real-world standards considerations.

What organization defines the overarching SQL standard used by relational databases?

The American National Standards Institute (ANSI).

What is the main benefit of having an ANSI SQL standard for developers and DBAs?

It enables SQL code to be portable and consistent across different database management systems, reducing vendor lock-in.

Which four basic data-manipulation commands are explicitly specified in the ANSI SQL standard?

SELECT, INSERT, UPDATE, and DELETE.

Besides query syntax, name two other areas that the ANSI SQL standard covers.

Data integrity (e.g., constraints) and transaction management (e.g., ACID properties).

Define the term “vendor lock-in.”

A situation in which an organization becomes so dependent on a vendor’s products or technologies that switching to another vendor becomes difficult or costly.

Give two proprietary commands different vendors use to limit returned rows and the vendors that use them.

TOP in Microsoft SQL Server and ROWNUM in Oracle.

How does MySQL create an auto-incrementing column, and what is the analogous keyword in SQL Server?

MySQL uses AUTO_INCREMENT; SQL Server uses IDENTITY.

What ANSI SQL syntax can replace vendor-specific auto-increment solutions?

GENERATED ALWAYS AS IDENTITY.

Why do many commercial databases include proprietary SQL extensions even after ANSI standardization?

To provide advanced features, differentiate their products, optimize performance, and satisfy existing customer expectations and legacy systems.

Is PostgreSQL fully ANSI SQL compliant?

No, but it adheres to a significant portion of the standard while also offering additional, non-standard features.

List three ANSI-compliant features that PostgreSQL supports.

Basic SQL syntax (SELECT, INSERT, etc.), ACID transaction management, and standard data integrity constraints (primary keys, foreign keys, etc.).

Name two advanced ANSI SQL features supported by PostgreSQL that aid complex queries.

Common Table Expressions (CTEs) and window functions.

What type of identifier does PostgreSQL support that guarantees global uniqueness, and what is its bit length?

Universally Unique Identifier (UUID), which is 128 bits long.

What ANSI SQL feature lets you define a temporary result set inside a query for readability and reuse?

Common Table Expressions (CTEs).

Explain ACID as it relates to PostgreSQL’s transaction support.

ACID stands for Atomicity, Consistency, Isolation, Durability—properties PostgreSQL implements to ensure reliable transaction processing.

Give two examples of non-standard reasons a company might avoid pure ANSI SQL.

Performance optimizations that rely on vendor-specific constructs and the high cost/time needed to migrate large legacy systems.

How does PostgreSQL’s extensibility complement its ANSI compliance?

Developers can add custom functions, data types, and procedural languages while still leveraging the standard SQL core for portability.

Why might abruptly forcing a team to switch from a familiar vendor’s SQL dialect to pure ANSI SQL be disruptive?

It can break existing workflows, require extensive retraining, and necessitate significant code changes, risking business interruptions.