There is a null in the MySQL database. Using comparison operators, under what circumstances the result returns 1. The comparison operator is used below to determine the result returned by null. The specific operation is as follows:
1. The comparison operator "=" cannot compare NULL, use The result of "=" comparison is null, as shown in the following figure:
##2. The comparison operator "" cannot be used for NULL comparison, and the returned result is null, as shown in the following figure:
##4. Comparison operators "
#5. The comparison operator "" can correctly compare NULL and the return value is 1, as shown in the following figure:
Notice
Familiar with the precedence of comparison operatorsUnderstand the comparison method of NULL values
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