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18 mar 2014 · IS NOT NULL returns everything that literally is not set to NULL, even the empty string "". !='', or <>'' as Ivan said in the accepted answer, will not return empty strings or NULL values. In other words IS NOT NULL is a subset of !='', but they are not equivalent.
29 lis 2019 · If you simply want to check if a column is null or empty, you may be better off doing this: SELECT myCol FROM MyTable WHERE MyCol IS NULL OR MyCol = '' See TRIM COALESCE and IS NULL for more info. Also Working with null values from the MySQL docs
6 cze 2024 · We can use the function NULLIF to compare and check if the column contains null or empty values: SELECT id, name FROM Department WHERE NULLIF(TRIM(code), '') IS NULL; The NULLIF function evaluates its two arguments, returning NULL if they are equal.
WHERE Syntax. SELECT column1, column2, ... FROM table_name. WHERE condition; Note: The WHERE clause is not only used in. SELECT statements, it is also used in UPDATE, DELETE, etc.!
The following statements show how to find the NULL phone number and the empty phone number: mysql> SELECT * FROM my_table WHERE phone IS NULL; mysql> SELECT * FROM my_table WHERE phone = ''; See Section 5.3.4.6, “Working with NULL Values”, for additional information and examples.
2 lut 2024 · To determine if a column is empty or null in MySQL, we utilize the IS NULL and IS NOT NULL conditions in a SELECT statement. To ascertain if a column is empty or null in SQL, use COALESCE(column, ”) or column IS NULL OR column = ”. These queries fetch rows where the specified column contains an empty string or null value, ensuring ...
This tutorial shows you how to use MySQL WHERE clause to filter rows based on specified conditions.
