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How do I insert a NULL value in a timestamp column?
In order to allow a TIMESTAMP to be nullable, create it using the NULL attribute, or alter the table and add the NULL attribute.
How do you set a field NULL in MySQL?
MySQL UPDATE command can be used to update a column value to NULL by setting column_name = NULL, where column_name is the name of the column to be updated. The following MySQL statement will update pub_lang column with NULL if purch_price is more than 50.
WHAT IS NULL value in MySQL?
Introduction to MySQL NULL values In MySQL, a NULL value means unknown. A NULL value is different from zero ( 0 ) or an empty string ” . A NULL value is not equal to anything, even itself. Generally, you use the NULL value to indicate that the data is missing, unknown, or not applicable.
What is default value of datetime in MySQL?
CREATE TABLE t1 ( ts1 TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, — default 0 ts2 TIMESTAMP NULL ON UPDATE CURRENT_TIMESTAMP — default NULL ); DATETIME has a default of NULL unless defined with the NOT NULL attribute, in which case the default is 0.
When to use default null for timestamp column?
DEFAULT NULL can be used to explicitly specify NULL as the default value. (For a TIMESTAMP column not declared with the NULL attribute, DEFAULT NULL is invalid.) If a TIMESTAMP column permits NULL values, assigning NULL sets it to NULL, not to the current timestamp.
How to declare null as the default value in MySQL?
To permit a TIMESTAMP column to contain NULL, explicitly declare it with the NULL attribute. In this case, the default value also becomes NULL unless overridden with a DEFAULT clause that specifies a different default value. DEFAULT NULL can be used to explicitly specify NULL as the default value.
How to enable explicit defaults for timestamp in MySQL?
Enable the explicit_defaults_for_timestamp system variable. In this case, the DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP clauses that specify automatic initialization and updating are available, but are not assigned to any TIMESTAMP column unless explicitly included in the column definition.
Are there any automatic timestamp columns in MySQL?
TIMESTAMP and DATETIME columns have no automatic properties unless they are specified explicitly, with this exception: If the explicit_defaults_for_timestamp system variable is disabled, the first TIMESTAMP column has both DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP if neither is specified explicitly.