What's the difference between “LIKE” and “=” in SQL?

Question

Is there any difference between:

SELECT * FROM users WHERE username=\"davyjones\"

and

SELECT * FROM users WHERE username LI         


        

Answer 1

LIKE supports wildcards. Usually it uses the % or _ character for the wildcard.

Using the LIKE operator with no wildcards is the same as using the = operator.

Answer 2

As far as I know, there is no difference but a time cost to the two selects you wrote. Usually one uses LIKE together with %, meaning 'any string'. I think there's also a character that can be used with LIKE for 'any character', not sure what that is without googling.

But as your two selects go, the only difference I see is a different run time, since LIKE is used in a regexp-sort-of-fashion.

Answer 3

Like gets you to work with wild card operators, you may use it in your case for like 'davyjon%' to get all the results starting with davyjon, and to get the exact you may place 'davyjones' and you may also use = in this case

Answer 4

As per SQL standard, the difference is treatment of trailing whitespace in CHAR columns. Example:

create table t1 ( c10 char(10) );
insert into t1 values ('davyjones');

select * from t1 where c10 = 'davyjones';
-- yields 1 row

select * from t1 where c10 like 'davyjones';
-- yields 0 rows

Of course, assuming you run this on a standard-compliant DBMS. BTW, this is one the main differences between CHARs and VARCHARs.

Answer 5

LIKE allows partial matching / use of wildcards, while = checks for exact matches.

For example

SELECT * FROM test WHERE field LIKE '%oom';

Will return rows where field value is any of the following:

Zoom, Boom, Loom, Groom

Answer 6

The LIKE condition allows you to use wildcards:

SELECT * FROM suppliers
WHERE supplier_name like 'Hew%';

See more examples.

and Equals = is used for equality matching.