Dropping Unique constraint from MySQL table

The Question :

205 people think this question is useful

How can I drop the “Unique Key Constraint” on a column of a MySQL table using phpMyAdmin?

The Question Comments :

The Answer 1

359 people think this answer is useful

A unique constraint is also an index.

First use SHOW INDEX FROM tbl_name to find out the name of the index. The name of the index is stored in the column called key_name in the results of that query.

Then you can use DROP INDEX:

DROP INDEX index_name ON tbl_name

or the ALTER TABLE syntax:

ALTER TABLE tbl_name DROP INDEX index_name

The Answer 2

124 people think this answer is useful

You can DROP a unique constraint from a table using phpMyAdmin as requested as shown in the table below. A unique constraint has been placed on the Wingspan field. The name of the constraint is the same as the field name, in this instance.

alt text

The Answer 3

11 people think this answer is useful

The indexes capable of placing a unique key constraint on a table are PRIMARY and UNIQUE indexes.

To remove the unique key constraint on a column but keep the index, you could remove and recreate the index with type INDEX.

Note that it is a good idea for all tables to have an index marked PRIMARY.

The Answer 4

4 people think this answer is useful

To add UNIQUE constraint using phpmyadmin, go to the structure of that table and find below and click that,

enter image description here

To remove the UNIQUE constraint, same way, go to the structure and scroll down till Indexes Tab and find below and click drop, enter image description here

Hope this works.

Enjoy 😉

The Answer 5

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For WAMP 3.0 : Click Structure Below Add 1 Column you will see ‘- Indexes’ Click -Indexes and drop whichever index you want.

The Answer 6

2 people think this answer is useful

If you want to remove unique constraints from mysql database table, use alter table with drop index.


create table unique_constraints(unid int,activity_name varchar(100),CONSTRAINT activty_uqniue UNIQUE(activity_name),primary key (unid));

alter table unique_constraints drop index activty_uqniue;

Where activty_uqniue is UNIQUE constraint for activity_name column.

The Answer 7

0 people think this answer is useful

The constraint could be removed with syntax:


As of MySQL 8.0.19, ALTER TABLE permits more general (and SQL standard) syntax for dropping and altering existing constraints of any type, where the constraint type is determined from the constraint name: ALTER TABLE tbl_name DROP CONSTRAINT symbol;



-- checking constraint name if autogenerated

-- dropping constraint

db<>fiddle demo

The Answer 8

-1 people think this answer is useful

while dropping unique key we use index

DROP INDEX  unique_address;

The Answer 9

-3 people think this answer is useful

my table name is buyers which has a unique constraint column emp_id now iam going to drop the emp_id

step 1: exec sp_helpindex buyers, see the image file

step 2: copy the index address

enter image description here

step3: alter table buyers drop constraint [UQ__buyers__1299A860D9793F2E] alter table buyers drop column emp_id



instead of buyers change it to your table name 🙂


thats all column name emp_id with constraints is dropped!

The Answer 10

-6 people think this answer is useful
  1. First delete table

  2. go to SQL

Use this code:

CREATE  TABLE service( --tablename 
  `serviceid` int(11) NOT NULL,--columns
  `customerid` varchar(20) DEFAULT NULL,--columns
  `dos` varchar(30) NOT NULL,--columns
  `productname` varchar(150) NOT NULL,--columns
  `modelnumber` bigint(12) NOT NULL,--columns
  `serialnumber` bigint(20) NOT NULL,--columns
  `serviceby` varchar(20) DEFAULT NULL--columns
INSERT INTO `service` (`serviceid`, `customerid`, `dos`, `productname`, `modelnumber`, `serialnumber`, `serviceby`) VALUES
(1, '1', '12/10/2018', 'mouse', 1234555, 234234324, '9999'),
(2, '09', '12/10/2018', 'vhbgj', 79746385, 18923984, '9999'),
(3, '23', '12/10/2018', 'mouse', 123455534, 11111123, '9999'),
(4, '23', '12/10/2018', 'mouse', 12345, 84848, '9999'),
(5, '546456', '12/10/2018', 'ughg', 772882, 457283, '9999'),
(6, '23', '12/10/2018', 'keyboard', 7878787878, 22222, '1'),
(7, '23', '12/10/2018', 'java', 11, 98908, '9999'),
(8, '128', '12/10/2018', 'mouse', 9912280626, 111111, '9999'),
(9, '23', '15/10/2018', 'hg', 29829354, 4564564646, '9999'),
(10, '12', '15/10/2018', '2', 5256, 888888, '9999');
--before droping table
ALTER TABLE `service`
  ADD PRIMARY KEY (`serviceid`),
  ADD  unique`modelnumber` (`modelnumber`),
  ADD  unique`serialnumber` (`serialnumber`),
  ADD unique`modelnumber_2` (`modelnumber`);
--after droping table
ALTER TABLE `service`
  ADD PRIMARY KEY (`serviceid`),
  ADD  modelnumber` (`modelnumber`),
  ADD  serialnumber` (`serialnumber`),
  ADD modelnumber_2` (`modelnumber`);


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