CODEWITHSUNDEEP
sqloracle-database
Niklas Siefke
Niklas Siefke

Reputation: 343

Unknown identifier with custom named columns

I guess its pretty easy to solve but I don't get it:

SELECT TO_NUMBER(PERS_NR) AS Spieler1, TO_NUMBER(PERS_NR) AS Spieler2 
FROM DBS_TAB_MITARBEITER 
WHERE Spieler1 < Spieler2;

I get an

unkown identifier

error in the where clause. Why?

Upvotes: 0

Views: 1275

Answers (1)

Patrick Hofman
Patrick Hofman

Reputation: 156958

Your where clause doesn't work since the fields aren't know at that moment yet. You have to use the real column names:

SELECT TO_NUMBER(PERS_NR) AS Spieler1, TO_NUMBER(PERS_NR) AS Spieler2 
FROM DBS_TAB_MITARBEITER 
WHERE TO_NUMBER(PERS_NR) < TO_NUMBER(PERS_NR);

When you do that, you immediately see that your query doesn't yield any rows since the where clause is impossible to result in a true.

Upvotes: 5

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