No empty strings in Oracle

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This was pretty easy to find, but considering how unexpected it is, I feel it's worth a mention.

There are no empty strings in Oracle's SQL or PL/SQL.

Consider -

myVar VARCHAR2(10) := '';

The following will never execute.

IF myVar = '' THEN
-- do something
END IF;

myVar must be compared to NULL for the block to work.

IF myVar IS NULL
-- do something
END IF;

Likewise

SELECT someField
FROM   someTable
WHERE  someField = '';

Will always return 0 rows.

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