Question

Can any one tell me the difference between replace function & translate function of Oracle?

I read somewhere that replace makes the changes in database permanent where translate does not, is it correct?

Can any one show the query which will prove that replace does changes permanently in database?

Answer 1

The difference between REPLACE and TRANSLATE:

• REPLACE substitutes one string for another string.
• TRANSLATE substitutes characters in one set for those in another.
• Neither TRANSLATE or REPLACE update the database.

Here’s some examples:

create table nada (id number(8), description nvarchar2(30));
insert into nada values (1, "I like peanuts.");
insert into nada values (2, 'Peanuts are not a nut.');
insert into nada values (3, 'peanuts are a legume.');
commit;
select * from nada;

Id Description
-- ------------------------
 1 I like peanuts.
 2 Peanuts are not a nut.
 3 peanuts are a legume.

REPLACE works like this:

select replace(description, 'peanuts', 'tomatoes') from nada;

gives:

replace(description,'peanuts','tomatoes')
--------------------------------------
I like tomatoes.
Peanuts are not a nut.
tomatoes are a legume.

Just the word ‘peanuts’ is replaced with ‘tomatoes’. It’s case sensitive so ‘Peanuts’ isn’t replaced.

TRANSLATE works like this:

select translate(description, ' .', '_!') from nada;

translate(description, ' .', '_!')
----------------------------------
I_like_peanuts!
Peanuts_are_not_a_nut!
peanuts_are_a_legume!

All spaces are changed to underscores and all periods are changed to bangs!

---

Neither TRANSLATE or REPLACE update the database. They just change the value
in a statement. Of course, you can use that value to update the database if
you want. For example:

select replace(description, 'peanuts', 'tomatoes') from nada;
select * from nada;

The table is still the same:

Id Description
-- ------------------------
 1 I like peanuts.
 2 Peanuts are not a nut.
 3 peanuts are a legume.

If you want to change the table, put it in an UPDATE or INSERT statement,
such as:

update nada set description = replace(description, 'peanuts', 'tomatoes');
commit;

Now it’s changed:

select * from nada;

Id Description
-- ------------------------
 1 I like tomatoes.
 2 Peanuts are not a nut.
 3 tomatoes are a legume.

Now if you want to fix ‘Peanuts’ too, you can use REGEXP_REPLACE.