Question

i am looking at some practice questions

Assume that you've just created this table:


CREATE TABLE timestamptest (
ts1 TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
i INT
);


When you look at its structure, you will notice that the TIMESTAMP column is declared NOT NULL. What happens if you insert these records:

mysql> INSERT INTO timestamptest SET ts1=NULL, i=10; 
mysql> INSERT INTO timestamptest SET ts1=0, i=11; 
mysql> INSERT INTO timestamptest SET ts1='', i=12;

the ans is

Only the first statement succeeds, and the TIMESTAMP column is set to the current date and time. The other two statements give an error:

mysql> INSERT INTO timestamptest SET ts1=NULL, i=10;
Query OK, 1 row affected (0.00 sec)

mysql> INSERT INTO timestamptest SET ts1=0, i=11;
ERROR 1292 (22007): Incorrect datetime value: '0' for column 'ts1' at row 1
mysql> INSERT INTO timestamptest SET ts1='', i=12;
ERROR 1292 (22007): Incorrect datetime value: '' for column 'ts1' at row 1

but when i tried, inserting ts1=0 works, it inserts a zero value timestamp … is the answer wrong?

Answer 1

It depends whether the NO_ZERO_DATE option is set:

mysql> create table foo(x timestamp);
Query OK, 0 rows affected (0.01 sec)

mysql> set sql_mode='';
Query OK, 0 rows affected (0.00 sec)

mysql> insert into foo values(0);
Query OK, 1 row affected (0.00 sec)

mysql> set sql_mode='strict_all_tables,no_zero_date';
Query OK, 0 rows affected (0.00 sec)

mysql> insert into foo values(0);
ERROR 1292 (22007): Incorrect datetime value: '0' for column 'x' at row 1