SQL Help Needed: Split & Replace - Update Column Vale

Question

Hello experts,
I would like to seek for your expertise on how to update part of the column's value for many rows.
Let say, I have a table (table1) with 2 columns (col1 & col2)
col1 col2
100 abc.123
200 abc.456
300 abc.789
and i need to update abc to efg for col2 to become like
col1 col2
100 efg.123
200 efg.456
300 efg.789
any clue on how should the query looks like ?
pls advise, many thanks.

Answer 1

For your given example, Michael's solution will work, however it may have problems if you had abc more than one time in a row.
For example, could you have a value like abc.123.abc in a row? If so, would you want to update it to efg.123.efg or to efg.123.abc?
If you want the firs, then Michael's is correct, if you want the second, then you would need something more like:
UPDATE table1
SET col2 = 'abc'||SUBSTR(col2, 4)
WHERE SUBSTR(col2, 1, 3) = 'abc'John