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Asked: 2026-06-04T20:16:50+00:00

This is my table with some sample data C ID | D ID |

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This is my table with some sample data

C ID | D ID    | Details |
--------------------------
 a   | b_data1 | d1      |
 a   | b_data2 | d2      |
 b   | b_data1 | d1      |
 b   | b_data2 | d2      |
 c   | b_data1 | d1      |
 c   | b_data2 | d2      |

When I run this query##

INSERT IGNORE INTO table_name (C_ID, D_ID, Details) VALUES ('C', 'b_data3','d3') ('C', 'b_data2','d2')

It inserts both those rows when it’s supposed to ignore the second value pair ('C', 'b_data2','d2')

No indexes /primary key are defined.

I want to make sure there is no duplicate row, means data in three columns combined should make the row unique. I can’t make it unique .As I have illustrated here, a can keep same content as b but a should not have a duplicate.

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1 Answer

  1. Editorial Team

    MySQL enforces unique constraints with UNIQUE indexes. If you wish to add the index without recreating the table, you would do:

    CREATE UNIQUE INDEX index_name ON table (C_ID, D_ID, Details)

    In addition to INSERT IGNORE and the already mentioned REPLACE, you can also use INSERT…ON DUPLICATE KEY UPDATE for more control over what happens when insert runs into a duplicate unique.

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