mysql - How can I fill empty cells with values from previous rows -

i have table looks following example. i'd replcae missing value (if any) in column previous value. table:

 col1      col2       0.1       0.2  0.23      0.53   -        0.46  0.77       -     -       0.32 

i expect following results:

 col1      col2   0.1       0.2  0.23      0.53  0.23      0.46  0.77      0.46   0.77      0.32 

in order this, you'll need sort of identifier previous row. hypothetically (since waiting clarification on 'previous' in example), let's have primary key identifier each row:

| id | col1 | col2 | +----+------+------+ | 1  | 0.1  | 0.2  | | 2  | 0.23 | 0.53 | | 3  | null | 0.46 | | 4  | 0.77 | null | | 5  | null | 0.32 | 

you can use value previous primary key update table. can join 2 tables on condition id matches previous one, , set col1 value accordingly this:

update mytable m join mytable mt on (m.id - 1) = mt.id set m.col1 = mt.col1 m.col1 null; 

to both columns in same update query, you'll need add if statement:

update mytable m join mytable mt on (m.id - 1) = mt.id set m.col1 =   case when m.col1 null     mt.col1   else     m.col1   end,   m.col2 =    case when m.col2 null     mt.col2   else      m.col2   end; 

here reference on conditional update, , sql fiddle example. can't run query, build schema option. edit answer results when can.

note not work if there 2 null values in row. if possible, need join rows on recent non-null id.