Question

I have a mysql table. How do I remove partial duplicates based on three columns? Is it posibble to apply the changes to the current table? If not what is the solution?

Example:
The current table
Surname………First Name…….Company Name……..Responsibilities…….Column5
McKain……………Christine………XYZ………………………….A…………………………..A
McKain………. ….Christine ………XYZ ………………………..B…………………………. B
Morrell…………… Sally …………..ABC …………………………A ………………………….A
Motu ………………Timothy……….. EFG ………………………..I …………………………..I

The resulting Table:

Surname………First Name…….Company Name……..Responsibilities…….Column5
McKain……………Christine………XYZ………………………….A…………………………..A
Morrell…………… Sally …………..ABC …………………………A ………………………….A
Motu ………………Timothy……….. EFG ………………………..I …………………………..I

and if possible someone please tell me an easy way to add a table here in stack overflow..

Answer 1

Replace tableName with your table’s name and the GROUP BY/UNIQUE INDEX fields with the fields you want to be unique.

Warning: The GROUP BY used will only select the first entry when removing duplicates.

If something goes wrong, you still have a copy of your original data in tableName_old.

-- Create a new table that's filtered
CREATE TABLE newTable
    (SELECT * 
    FROM tableName
    GROUP BY LastName, FirstName, Company);

-- Add a unique index of the fields you want
ALTER TABLE newTable ADD UNIQUE INDEX ix_unique (LastName, FirstName, Company);

-- Rename the tables around
RENAME TABLE tableName TO tableName_old;
RENAME TABLE newTable TO tableName;