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improved formatting; minor typo fixes
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edit approved Sep 14, 2011 at 22:22
Nick Chammas
edit approved Sep 14, 2011 at 22:22
Nick Chammas
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DUALDUAL is a table with has exactly one row as the following SQL statement will show:

SELECT * FROM dual;

SELECT * FROM dual;

Your dual2dual2 table has notno rows. If you insert one, you will see the same behavior.

4*5 is an expression that oracleOracle can evaluate without actually using data from the table. It will evaluate it once for every row, just like it would do with a normal column expression. So if there is no row, no result is returned, if there are two rows, you will get the 20 twice.

DUAL is a table with has exactly one row as the following SQL statement will show:

SELECT * FROM dual;

Your dual2 table has not rows. If you insert one, you will see the same behavior.

4*5 is an expression that oracle can evaluate without actually using data from the table. It will evaluate it once for every row, just like it would do with a normal column expression. So if there is no row, no result is returned, if there are two rows, you will get the 20 twice.

DUAL is a table with has exactly one row as the following SQL statement will show:

SELECT * FROM dual;

Your dual2 table has no rows. If you insert one, you will see the same behavior.

4*5 is an expression that Oracle can evaluate without actually using data from the table. It will evaluate it once for every row, just like it would do with a normal column expression. So if there is no row, no result is returned, if there are two rows, you will get the 20 twice.

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Hendrik Brummermann
Hendrik Brummermann
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DUAL is a table with has exactly one row as the following SQL statement will show:

SELECT * FROM dual;

Your dual2 table has not rows. If you insert one, you will see the same behavior.

4*5 is an expression that oracle can evaluate without actually using data from the table. It will evaluate it once for every row, just like it would do with a normal column expression. So if there is no row, no result is returned, if there are two rows, you will get the 20 twice.