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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.

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.

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

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

Example:

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.

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

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

Hope this works.

Enjoy ;)

while dropping unique key we use index

ALTER TABLE tbl

DROP INDEX  unique_address;

1.First delete table

2.go to sql

CREATE  TABLE service( --tablename 

  `serviceid` int(11) NOT NULL,--coloums

  `customerid` varchar(20) DEFAULT NULL,--coloums

  `dos` varchar(30) NOT NULL,--coloums

  `productname` varchar(150) NOT NULL,--coloums

  `modelnumber` bigint(12) NOT NULL,--coloums

  `serialnumber` bigint(20) NOT NULL,--coloums

  `serviceby` varchar(20) DEFAULT NULL--coloums

)

--INSERT VALUES

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`);

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

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

note:

Blockquote

instead of buyers change it to your table name :)

Blockquote

thats all column name emp_id with constraints is dropped!