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SQL Programming > Learn SQL Programming > Why does my SQL query return duplicates?
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Why does my SQL query return duplicates?

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Your SQL query may return duplicates due to several reasons, such as not using the `DISTINCT` keyword, joining multiple tables without proper conditions, or the presence of duplicate data in the database itself. To eliminate duplicates, ensure that you use `DISTINCT` in your `SELECT` statement or refine...
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Your SQL query may return duplicates due to several reasons, such as not using the `DISTINCT` keyword, joining multiple tables without proper conditions, or the presence of duplicate data in the database itself. To eliminate duplicates, ensure that you use `DISTINCT` in your `SELECT` statement or refine your `JOIN` conditions to avoid unnecessary duplications.

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Your SQL query may return duplicates due to several reasons: 1. **Missing DISTINCT**: If you're selecting columns without using the `DISTINCT` keyword, it will return all rows, including duplicates. ```sql SELECT DISTINCT column_name FROM table_name; ``` 2. **Join Conditions**: When...
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Your SQL query may return duplicates due to several reasons: 1. **Missing DISTINCT**: If you're selecting columns without using the `DISTINCT` keyword, it will return all rows, including duplicates. ```sql SELECT DISTINCT column_name FROM table_name; ``` 2. **Join Conditions**: When using JOINs, if the join conditions are not properly defined, you may end up with multiple matches, leading to duplicate rows. 3. **Data Issues**: The underlying data itself may contain duplicates. Check your table for repeated entries. 4. **Group By**: If using `GROUP BY`, ensure you're aggregating correctly to avoid duplicates. ```sql SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name; ``` 5. **Subqueries**: If you're using subqueries, ensure they return unique results as expected. To resolve duplicates, review your query structure and the data being queried, adjusting as necessary. read less
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