How to evaluate two tables column cell values?

user_19410045 0
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I have two tables:

customerTable:

| customerID | name | address |

receiptTable

| receiptID | customerNumber | products |

This is my query:

SELECT customerID, customerNumber 
FROM customerTable, receiptTable 
WHERE customerID != customerNumber

What I'm trying to do is get rows of customerID's only if it's not in the receipt table, I really don't even know how to ask this. I apologize.

sql
1 Answers

Try this:

SELECT customerID, customerNumber 
FROM customerTable 
     LEFT JOIN receiptTable  ON customerID = customerNumber
WHERE customerNumber is NULL
user_62032110
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