SUBQUERY in PostgreSQL - Examples & AI Generator

SUBQUERYs in PostgreSQL allow you to nest queries inside other queries to solve complex business logic, such as filtering records based on aggregates or matching results across tables. While powerful, the PostgreSQL SUBQUERY syntax can be tricky and easy to mistype, especially when switching from other databases or handling correlated subqueries. AI2sql removes the manual guesswork—just describe your need in plain language and get a production-ready SUBQUERY in seconds, no coding skills required.

SUBQUERY Syntax in PostgreSQL

General Syntax

SELECT column1, column2
FROM table1
WHERE columnX <operator> (SELECT columnY FROM table2 WHERE condition);
<

• PostgreSQL supports scalar, row, and table-based SUBQUERYs.

• Parentheses are required around SUBQUERY statements.

• Operators like IN, EXISTS, =, > work with SUBQUERYs.

SUBQUERY Examples You Can Generate Instantly

1. Customers Who Placed Orders Over $1000

SELECT customer_id, name
FROM customers
WHERE customer_id IN (
  SELECT customer_id
  FROM orders
  WHERE total > 1000
);

2. Products Not Ordered in the Last 30 Days

SELECT product_id, product_name
FROM products
WHERE product_id NOT IN (
  SELECT product_id
  FROM orders
  WHERE order_date > NOW() - INTERVAL '30 days'
);

3. Orders Containing More Items Than the Average

SELECT order_id, item_count
FROM orders
WHERE item_count > (
  SELECT AVG(item_count) FROM orders
);

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Why Use AI2sql Instead of Manual SUBQUERY Coding

• No coding required: Skip intricate PostgreSQL SUBQUERY syntax.

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FAQ: SUBQUERY in PostgreSQL

Are SUBQUERYs in PostgreSQL different from other databases?

Yes—PostgreSQL enforces parentheses, and its optimizer handles correlated and non-correlated SUBQUERYs efficiently. Syntax may differ from MySQL or SQL Server.

Can I use multiple levels of SUBQUERY?

Absolutely. PostgreSQL allows nested SUBQUERYs within SELECT, WHERE, or FROM clauses, though clarity and performance should be considered.

What's a common mistake with SUBQUERYs?

Forgetting required parentheses or using an operator incompatible with the SUBQUERY's return type. AI2sql automatically handles these PostgreSQL-specific rules.

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Conclusion: Crafting PostgreSQL SUBQUERYs no longer requires memorizing complex syntax or risking small mistakes. With AI2sql, go from question to production-ready SQL in 10 seconds—no coding, no wait, just results. Generate your first SUBQUERY now and join 50,000+ professionals worldwide.