The default bar,
Update TableName time the SET field = ''
SQL SERVER will automatically add "1900-01-01"
Update TableName time the SET field = null
would not be a
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null values do not, others will. In the system, time is not a string, but with a decimal number - the number of days after the integer portion represents from 1 January 1900, the fractional part is the number of milliseconds after midnight (like).
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datetime / smalldatetime storage format is fixed.
by the date + time components.
If the store only time, it will automatically add 1900-1-1
unless you use character fields to store
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datetime type system which is common to store 8 bytes, the type of digital storage.
Wherein the first four bytes are used 1900-1-1 days before / after the date of storage,
wherein the 4 bytes to store the number of milliseconds after 00:00.
If '' it is the 1900-1-1.
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Check before being stored, if it is set to NULL is empty
or take the time to check if it is 1900-01-01, then the empty set, but when this is the case there will be problems printing, it is recommended to use the front One way