Names of the customers whose loan amount (L_Amt) is above 1000000.

Q: Names of the customers whose loan amount (L_Amt) is above 1000000.

**SQL Query:** ```sql SELECT C_Name FROM CUSTOMERS, LOANS WHERE CUSTOMERS.C_ID = LOANS.C_ID AND L_Amt > 1000000; ``` This joins CUSTOMERS and LOANS on the common column C_ID and returns only the names of customers whose loan amount exceeds ₹10,00,000.

Structured Query Language (SQL)

SQL Join between CUSTOMERS and LOANS using Common Key C_ID

Official Answer

SQL Query:

``sql


SELECT C_Name FROM CUSTOMERS, LOANS
WHERE CUSTOMERS.CID = LOANS.CID AND L_Amt > 1000000;

This joins CUSTOMERS and LOANS on the common column C_ID and returns only the names of customers whose loan amount exceeds ₹10,00,000.

equi-joincommon column C_IDWHERE clause ANDcartesian producttwo-table SQL queryL_Amt

Marking Scheme

11 mark for the complete correct query with the join condition CUSTOMERS.C_ID = LOANS.C_ID and the filter L_Amt > 1000000; marks deducted if the join condition is missing.

Hint

Two-table questions need a join condition (common column) ANDed with the actual filter condition.

Quick Oral Answer

I join CUSTOMERS and LOANS on C_ID and then filter for L_Amt above 1000000, selecting only C_Name from the matched rows.

Analysis & Explanation

Since customer names live in CUSTOMERS but the loan amount lives in LOANS, the two tables must be joined before filtering.

Concept

The join condition CUSTOMERS.CID = LOANS.CID matches each loan to its owning customer.
The AND L_Amt > 1000000 condition then restricts the joined rows to high-value loans only.

Exam trap

Forgetting the join condition produces a Cartesian product, matching every customer with every loan regardless of ownership — a serious logical error.

Common Mistakes

1Omitting the join condition CUSTOMERS.C_ID = LOANS.C_ID, which produces every possible customer-loan combination instead of matched pairs.
2Forgetting that C_Name exists only in CUSTOMERS, not LOANS, and trying to select it without joining the tables.

Interesting Facts

A join without a matching condition is called a Cartesian product and can return N x M rows for tables of size N and M — a classic accidental-query mistake in real databases.

This comma-style implicit join is the classic-SQL equivalent of writing 'FROM CUSTOMERS INNER JOIN LOANS ON CUSTOMERS.C_ID = LOANS.C_ID', which CBSE also accepts.

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Frequently Asked Questions

Why can't C_Name be selected directly from LOANS?

Because C_Name is a column in CUSTOMERS, not in LOANS; the two tables must be joined on C_ID before C_Name can be retrieved alongside loan details.

What happens if the join condition is left out?

SQL performs a Cartesian product, pairing every row of CUSTOMERS with every row of LOANS, which is both logically wrong and can return an enormous, meaningless result set.