Performing Smart Analytics and AI on GCP: What’s Wrong with This SQL Query? Common Errors in SELECT Statements

Learn why your SQL query isn’t executing due to syntax issues. Discover how to fix errors in selecting multiple columns using proper SQL syntax for efficient data retrieval.

Question

You wrote the following query, but it will not run execute due to errors:

SELECT table1.column1 and table2.column1
FROM table1 
INNER JOIN table2 ON table1.id = table2.id

What’s wrong with this query?

A. The and should be updated to a comma to select multiple fields.
B. SELECT and FROM must be in lowercase.
C. The table needs an explicit alias defined when using multiple columns.
D. The connection string must be specified in the from statement.

Answer

A. The and should be updated to a comma to select multiple fields.

Explanation

The issue with the provided SQL query lies in the use of the word “and” in the SELECT statement. In SQL, when selecting multiple columns, their names must be separated by commas, not the conjunction “and.” Here’s a breakdown of why this is incorrect and how to fix it:

Original Query

SELECT table1.column1 and table2.column1
FROM table1 
INNER JOIN table2 ON table1.id = table2.id

Why It’s Incorrect

• The SELECT clause uses “and” instead of a comma to separate column names.
• SQL syntax requires that column names be separated by commas when selecting multiple fields from one or more tables.

Corrected Query

SELECT table1.column1, table2.column1
FROM table1 
INNER JOIN table2 ON table1.id = table2.id

Key Points to Remember

• Comma Separation: Always use commas to separate column names in the SELECT clause when retrieving multiple fields from a database.
• No Case Sensitivity for Keywords: SQL keywords like SELECT and FROM are not case-sensitive, so writing them in uppercase or lowercase will not cause errors (eliminating Option B as a valid answer).
• Aliases Are Optional: Explicit aliases for tables are not mandatory unless there’s ambiguity in column names (eliminating Option C).
• Connection String Irrelevance: Connection strings are unrelated to the syntax of a query and are used for database connectivity, not within the query itself (eliminating Option D).

By replacing “and” with a comma, the query adheres to SQL standards and will execute correctly.

Performing Smart Analytics and AI on Google Cloud Platform skill assessment practice question and answer (Q&A) dump including multiple choice questions (MCQ) and objective type questions, with detail explanation and reference available free, helpful to pass the Performing Smart Analytics and AI on Google Cloud Platform exam and earn Performing Smart Analytics and AI on Google Cloud Platform certification.