(Note) how to judge whether the database field is not null or not ""

Now, I want to update the records with all departments empty to the manufacturing department, whose language is updateuserlistsetdept. The manufacturing department wheredept. However, I am prompted to make 0 records, and check that the records are not updated, I don't know what the empty record represents in SQL. I cannot use the field name null !!!

Now I want to update all records with empty departments to 'manufacturing amount'. The syntax is update userlist set dept = 'manufacturing amount' where dept = '', but 0 records are prompted, the record is not updated. I do not know what the empty record is represented in SQL. I cannot use field name = null !!! ========================================

Now I want to update all records with empty departments to 'manufacturing amount'. The syntax is update userlist set dept = 'manufacturing amount' where dept = '', but 0 records are prompted, the record is not updated. I do not know what the empty record is represented in SQL. I cannot use field name = null !!!

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Where dept is null

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It is usually determined in the program,
Null is also a special value in MSSQL. It can only be determined by is null or is not null,
Not empty, simple. <> ''..