Which of the following is the correct syntax to create an expression index on the uppercased username column in PostgreSQL?

easy📝 Syntax Q3 of 15

PostgreSQL - Indexing Strategies

Which of the following is the correct syntax to create an expression index on the uppercased username column in PostgreSQL?

ACREATE INDEX idx_upper_username ON users (UPPER(username));

BCREATE INDEX idx_upper_username ON users USING UPPER(username);

CCREATE INDEX idx_upper_username ON users WHERE UPPER(username);

DCREATE INDEX idx_upper_username ON users (username UPPER);

Step-by-Step Solution

Solution:

Step 1: Recall expression index syntax
The correct syntax uses CREATE INDEX index_name ON table_name (expression); where expression can be a function like UPPER(column).
Step 2: Check each option
CREATE INDEX idx_upper_username ON users (UPPER(username)); matches the correct syntax. Options A, B, and C use incorrect keywords or order.
Final Answer:
CREATE INDEX idx_upper_username ON users (UPPER(username)); -> Option A
Quick Check:
Expression index syntax = CREATE INDEX ON table (expression) [OK]

Quick Trick: Use parentheses around the expression in CREATE INDEX [OK]

Common Mistakes:

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