Can we join 2 tables without common column?
Yes, you can! The longer answer is yes, there are a few ways to combine two tables without a common column, including CROSS JOIN (Cartesian product) and UNION. The latter is technically not a join but can be handy for merging tables in SQL. In this article, I’ll guide you through the different solutions with examples.
How can we avoid duplicate records in SQL while joining two tables?
Good answer: Use the correct Primary and Foreign Keys to join the tables. This will avoid the dreaded Cartesian Product, with many times the desired number of returned rows most of which are duplicates. Good answer: Use the correct Primary and Foreign Keys to join the tables.
Why is my join query returning duplicates?
Answer: Query is a way to group records; it is not a reporting tool. The query output simply shows you whether the record belongs in the query. If a field with a one-to-many relationship is in your filters, output, or sort, the record will appear multiple times– once for each time the record meets the criteria.
Can we join two tables without primary key?
Yes we can. No Clause says that for joining of two or more tables there must be a foreign key or primary key constraint. For join we need to satisfy the conditions using on or where clause as per our requirements.
How do you remove duplicates without using distinct?
Below are alternate solutions :
- Remove Duplicates Using Row_Number. WITH CTE (Col1, Col2, Col3, DuplicateCount) AS ( SELECT Col1, Col2, Col3, ROW_NUMBER() OVER(PARTITION BY Col1, Col2, Col3 ORDER BY Col1) AS DuplicateCount FROM MyTable ) SELECT * from CTE Where DuplicateCount = 1.
- Remove Duplicates using group By.
How remove duplicate rows in join query?
Solution. Select column values in a specific order within rows to make rows with duplicate sets of values identical. Then you can use SELECT DISTINCT to remove duplicates.
How do I eliminate duplicate rows in two tables?
The SQL UNION ALL operator is used to combine the result sets of 2 or more SELECT statements. It does not remove duplicate rows between the various SELECT statements (all rows are returned). Each SELECT statement within the UNION ALL must have the same number of fields in the result sets with similar data types.
How do you avoid duplicates in join?
Solution. Select column values in a specific order within rows to make rows with duplicate sets of values identical. Then you can use SELECT DISTINCT to remove duplicates. Alternatively, retrieve rows in such a way that near-duplicates are not even selected.
How do I make a query without duplicates?
In the Navigation Pane, right-click the table that contains the field, and then click Design View. Select the field that you want to make sure has unique values. In the Field Properties pane at the bottom of the table design view, on the General tab, set the Indexed property to Yes (No duplicates).