Want Row Number on Group of column in MY SQL?

Question

I have one table in MYSQL It has data like

Id Name 
1  test
1  test
1  test123
2  test222
3  test333

I want the data like

Id Name     RowNum
1  test       1
1  test       2
1  test123    1
2  test222    1
3  test333    1

Means i want assign row number on group of Id and Name ?

what should the script for same?

Answer 1

UPDATE tablename SET RowNum=(SELECT COUNT(Id) FROM tablename WHERE Id=Name)

Answer 2

This table definition will achieve what you want.

CREATE TABLE  `test` (
  `Id` int(10) unsigned NOT NULL,
  `Name` varchar(45) NOT NULL,
  `RowNum` int(10) unsigned NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`Id`,`Name`,`RowNum`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

Populate table with data

INSERT INTO test VALUES
(1,"test",null),
(1,"test",null),
(1,"test123",null),
(2,"test222",null),
(3,"test333",null);

Select data from table

SELECT * FROM test;

Result

1, 'test', 1
1, 'test', 2
1, 'test123', 1
2, 'test222', 1
3, 'test333', 1

For doing it in a query here is a rather crude way of doing it.

select g.id,g.name,g.rownum 
from (
    select t.id,t.name,
        @running:=if(@previous=concat(t.id,t.name),@running,0) + 1 as rownum,
        @previous:=concat(t.id,t.name) 
    from test t
) g;

Answer 3

Oracle and MSSQL would support

SELECT Id, Name, row_number() OVER(partition by Id, Name order by Id) AS RowNum FROM table

(answer doesn't help the OP who is on MySQL, but added for completeness)