Add SQL for finding duplicate records

rosenfeld · Aug 3, 2011 · ba6b25f · ba6b25f
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diff --git a/en/databases/sql/finding-duplicates.md b/en/databases/sql/finding-duplicates.md
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+# Finding duplicate records with same column(s) value
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+Sometimes, this is useful if you have an inconsistent database and are unable to create a unique index in 2 fields:
+
+    SELECT * FROM table_name a WHERE 1 < (SELECT count(*) FROM table_name b WHERE a.column1 = b.column1 AND a.column2 = b.column2)