The following query can be used to delete rows with
duplicate values from a table. This is very useful when the table is large and
there are a lot of duplicate values.
The table must have a primary key or other unique field which can be
used to identify the duplicate records. If the table does not have a
primary key or other unique field it can be added. See my post Adding a primary key to a table.
Example:
In this example id is the primary key and student_no 000113,
000313, 000413. 000613 and 000913 are duplicated.
The following query will delete the duplicate rows:
The result:
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