Useful tips

Is null in MySQL query?

Is null in MySQL query?

To search for column values that are NULL , you cannot use an expr = NULL test. The following statement returns no rows, because expr = NULL is never true for any expression: mysql> SELECT * FROM my_table WHERE phone = NULL; To look for NULL values, you must use the IS NULL test.

IS NULL in if condition in MySQL?

MySQL IFNULL() function MySQL IFNULL() takes two expressions and if the first expression is not NULL, it returns the first expression. Otherwise, it returns the second expression. Depending on the context in which it is used, it returns either numeric or string value.

What is the use of if null ()?

Returns a Boolean value that indicates whether an expression contains no valid data (Null). The required expressionargument is a Variant containing a numeric expression or string expression. IsNull returns True if expression is Null; otherwise, IsNull returns False.


If expr1 is not NULL, IFNULL() returns expr1; otherwise it returns expr2. IFNULL() returns a numeric or string value, depending on the context in which it is used. You can use coalesce(column_name,0) instead of just column_name .

Why does MySQL accept null quantity instead of 0?

My sql table now accepted to record null quantity instead of 0 The problem you had is most likely because mysql differentiates between null written in capital letters and null written in small case. So if you used an update statement with null, it would not work. If you set it to NULL, it would work fine.

How to set an email to null in MySQL?

Because the phone number is missing, so a NULL value is used. Because the default value of the email column is NULL, you can omit the email in the INSERT statement as follows: To set the value of a column to NULL, you use the assignment operator ( = ).

How does MySQL handle null values in integer column?

For some data types, MySQL handles NULL values specially. If you insert NULL into a TIMESTAMP column, the current date and time is inserted. If you insert NULL into an integer or floating-point column that has the AUTO_INCREMENT attribute, the next number in the sequence is inserted.

How does the ifnull function in MySQL work?

The IFNULL function accepts two parameters. The IFNULL function returns the first argument if it is not NULL, otherwise, it returns the second argument. For example, the following statement returns the phone number if it is not NULL otherwise, it returns N/A instead of NULL.