About OID and the commands/operators STRING( ... ) ..AS and +

Hi,

I suspect that OID are reused, but how fast are they reused?

And does PostgreSQL support the STRING and AS command?

What I want to do is:

SELECT STRING( "IntegerKeyColumn" ) + STRING( "StringKeyColumn" ) +
TRING( "DoubleKeyColumn" ) AS STROID FROM "MyTable"

...and I want to be able to:

SELECT IntegerKeyColumn FROM "MyTable" WHERE
    STRING( "IntegerKeyColumn" ) + STRING( "StringKeyColumn" ) +
TRING( "DoubleKeyColumn" ) = [the result from previous select]

I would try it myself, but my PostgreSQL installation stopped working
(actually the whole computer is shutdown).

// Jarmo