Where Not Exists

[marco_puccetti]

Hello, can you help me to understand this script:

TABLE A:

LOAD IBAN,

  IBAN AS IBAN_KEY,

  STATO_TMP AS STATO

Resident FLUSSO_A;

Concatenate

LOAD IBAN,

  IBAN AS IBAN_KEY,

  'BLANK' AS STATO

Resident FLUSSO_B

WHERE NOT Exists(IBAN_KEY,IBAN);

In particular can you explain me how is it used the "Not Exits" formula and its meaning?

Thanks

[awhitfield]

It means that the data from the Concatenate part of the load will only be loaded if the IBAN,

  IBAN AS IBAN_KEY, are not already in TABLE A.

andy

[JonnyPoole]

"WHERE NOT Exists(IBAN_KEY,IBAN);"

this is going to check the IBAN value in each record in the 2nd load to see if that value already exists already in the list of all values that have been loaded and aliased as IBAN_KEY arlready in the first load.

So bascially it won't load the same IBAN value twice if its already been loaded.

[marco_puccetti]

Thanks!