Saturday, February 7, 2015
As a developer we always forget how to query for records with NULL values, no matter how many times we do it. It's just weird. Our first instinct is to write the query as such
But that will not return any results. The funny thing is there's no SQL error so you think that there's no results. However if you change the query to this
You see there's plenty of records with Region IS NULL
The reverse is true if you want records that are not NULL you would not write the query like this
But you want to write the query like this instead
SELECT CompanyName, ContactName, ContactTitle,Region FROM Customers WHERE Region = NULL
But that will not return any results. The funny thing is there's no SQL error so you think that there's no results. However if you change the query to this
SELECT CompanyName, ContactName, ContactTitle,Region FROM Customers WHERE Region IS NULL
You see there's plenty of records with Region IS NULL
The reverse is true if you want records that are not NULL you would not write the query like this
SELECT CompanyName, ContactName, ContactTitle,Region FROM Customers WHERE Region != NULL
But you want to write the query like this instead
SELECT CompanyName, ContactName, ContactTitle,Region FROM Customers WHERE Region IS NOT NULL
Subscribe to:
Post Comments (Atom)
Liên hệ Aivivu, đặt vé máy bay tham khảo
ReplyDeleteVé máy bay đi Mỹ
lịch bay từ mỹ về việt nam
vé máy bay từ đức về sài gòn
lịch bay từ hà nội đến nga
chuyến bay từ anh về việt nam
lịch bay từ pháp về việt nam
chuyen bay chuyen gia
947F909AC3
ReplyDeletetiktok takipçi satın al
black swivel accent chair
E66F8B61CC
ReplyDeleteGörüntülü Seks
Sanal Seks
Webcam Show
ReplyDeleteIn der Praxis wird oft vergessen, dass das vollständige Festplatten-Image nur dann rechtssicher ist, wenn es mit einer Hash-Summe wie MD5 oder SHA-256 validiert wurde. Diese Prüfwerte stellen sicher, dass kein Datenmanipulation stattgefunden hat und sind in deutschen Gerichtsverfahren anerkannt. Das Bundeskriminalamt fordert seit 2021 bei digitalen Beweisen den Nachweis der Integrität durch solche Prüfsummen. Fehlerhafte Dokumentation kann im späteren Verfahren zur Ungültigkeit des Beweises führen.