SQL Null
NULL is a special value that matches missed data. It means there is no data inserted into the field.
There are operators to detect whether the value is NULL:
IS NULL: detects only values that equal to NULLIS NOT NULL: detects values that are not NULL.
12SELECT title FROM songs WHERE album IS NOT NULL
NULLdoes not match 0 or empty line, it only matches data that is missing and does not exist.
NULLvalues are ignored in theMIN,MAX,COUNT,AVG, andSUMaggregate functions.
Danke für Ihr Feedback!
single
Fragen Sie AI
Fragen Sie AI
Fragen Sie alles oder probieren Sie eine der vorgeschlagenen Fragen, um unser Gespräch zu beginnen
Awesome!
Completion rate improved to 4.17SQL Null
Swipe um das Menü anzuzeigen
NULL is a special value that matches missed data. It means there is no data inserted into the field.
There are operators to detect whether the value is NULL:
IS NULL: detects only values that equal to NULLIS NOT NULL: detects values that are not NULL.
12SELECT title FROM songs WHERE album IS NOT NULL
NULLdoes not match 0 or empty line, it only matches data that is missing and does not exist.
NULLvalues are ignored in theMIN,MAX,COUNT,AVG, andSUMaggregate functions.
Wechseln Sie zum Desktop, um in der realen Welt zu übenFahren Sie dort fort, wo Sie sind, indem Sie eine der folgenden Optionen verwendenDanke für Ihr Feedback!
Awesome!
Completion rate improved to 4.17single
