How to compare strings in sql ignoring case?

If you are matching the full value of the field use

WHERE UPPER(fieldName) = 'ANGEL'

EDIT: From your comment you want to use:

SELECT 
    RPAD(a.name, 10,'=') "Nombre del Cliente"
    , RPAD(b.name, 12,'*') "Nombre del Consumidor" 
FROM 
    s_customer a, 
    s_region b 
WHERE 
    a.region_id = b.id 
    AND UPPER(a.name) LIKE '%SPORT%' 

You could use the UPPER keyword:

SELECT *
FROM Customers
WHERE UPPER(LastName) = UPPER('AnGel')

You can use:

select * from your_table where upper(your_column) like '%ANGEL%'

Otherwise, you can use:

select * from your_table where upper(your_column) = 'ANGEL'

Which will be more efficient if you are looking for a match with no additional characters before or after your_column field as Gary Ray suggested in his comments.

More detail on Mr Dredel's answer and tuinstoel's comment. The data in the column will be stored in its specific case, but you can change your session's case-sensitivity for matching.

You can change either the session or the database to use linguistic or case insensitive searching. You can also set up indexes to use particular sort orders.

eg

ALTER SESSION SET NLS_SORT=BINARY_CI;

Once you start getting into non-english languages, with accents and so on, there's additional support for accent-insensitive. Some of the capabilities vary by version, so check out the Globablization document for your particular version of Oracle. The latest (11g) is here

SELECT STRCMP("string1", "string2");

this returns 0 if the strings are equal.

• If string1 = string2, this function returns 0 (ignoring the case)
• If string1 < string2, this function returns -1
• If string1 > string2, this function returns 1

https://www.w3schools.com/sql/func_mysql_strcmp.asp

To avoid string conversions comparisons, use COLLATE SQL_Latin1_General_CP1_CI_AS.

EXAMPLE:

SELECT UserName FROM Users
WHERE UserName COLLATE SQL_Latin1_General_CP1_CI_AS = 'Angel'

That will return any usernames, whether ANGEL, angel, or Angel, etc.

I don't recall the exact syntax, but you may set the table column to be case insensitive. But be careful because then you won't be able to match based on case anymore and if you WANT 'cool' to not match 'CoOl' it will no longer be possible.