Mysql's method to check whether the field is empty

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Mysql's method to check whether the field is empty: 1. The query is not empty and the code is [Select * From table_name Where idled empty fields']; 2, the query is empty and the code is [Select * From table_name WhereISNULL (I)].

Mysql's method to check whether the field is empty:

Different databases in the sql standard use different functions. Today, we found that the query ranking function in mysql does not support top in MySQL. This top function is a function of sql server.

Briefly talk about the null and non-empty query methods in MySQL. Null divided into empty string''; and null

1. Not empty

Select * From table_name Where id''Select * From table_name Where idlers

2. Empty

Select * From table_name Where id=''Select * From table_name Where ISNULL (id)

Specific analysis, if the field is char and Varchar type can use id=''; if the int type is better with ISNULL.

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