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I don't know if you have any knowledge about how to deal with similar MySQL datasheet field values of NULL. Today, I'm here to talk about it briefly. If you are interested, let's take a look at the body. I believe you will gain something after reading the MySQL datasheet field value of how NULL should be handled.

In the process of creating a data table, some data fields need to set data values, which can be default values or empty null. At that time, the query statement did not work on the fields, so what keywords does mysql use? IS NULL,IS NOT NULL, the following details its usage. 1. Create data table create table dc3688_test_tbl- > (- > dc3688_author varchar (40) NOT NULL,- > dc3688_count INT- >); 2, query does not work mysql > SELECT * FROM dc3688_test_tbl WHERE dc3688_count = NULL;Empty set (0.00 sec) mysql > SELECT * FROM dc3688_test_tbl WHERE dc3688_count! = NULL Empty set (0.01 sec) 3, use IS NULL,IS NOT NULL SELECT * FROM dc3688_test_tbl WHERE runoob_count IS NULL SELECT * from dc3688_test_tbl WHERE runoob_count IS NOT NULL 4 to deal with null using the keyword isset ($count)

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