This feature is a hack intended for testing, but it’s built in to every Oracle installation.
DUAL is a table automatically created by Oracle and accessible to all users. It has one column, DUMMY, containing one row. It’s useful for selecting a constant or expression, because the table always exists (so the query will succeed) and […]
2 September 2003
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By Bennett
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Topics: Testing, SQL
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According to the documentation, the Oracle DATE type does not store fractions of a second. So if you store a date/time value including fractions of a second and read it back, you’ll get back a slightly different date/time. This will cause exact date matching code in your appplication to fail.
28 April 2003
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By Bennett
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Topics: Risks, SQL
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In Oracle 8, there is no such thing as a zero-length string. Any zero-length string, either from a function call or the literal ”, is treated as null.
26 April 2003
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By Bennett
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Topics: Risks, SQL
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Think carefully before using an automatically-generated unique ID as a primary key in a SQL table. Using such automatically-generated IDs introduces extra implementation detail. This is a pain to manage, especially if they are used as primary keys or worse, foreign keys in tables.