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MySQLi Articles
Page 117 of 341
How can we provide a date with only year (zero months & zero days) value in MySQL?
We can store a date with only year value and have zero months as well as zero-days in MySQL table by disabling NO_ZERO_IN_DATE mode. If this mode is enabled then MySQL will count such kind of date as invalid date and stores all zeros.mysql> Insert into year_testing (OrderDate) values('2017:00:00'); Query OK, 1 row affected (0.09 sec) mysql> select * from year_testing; +------------+ | OrderDate | +------------+ | 2017-00-00 | +------------+ 1 row in set (0.00 sec) mysql> SET sql_mode = 'NO_ZERO_IN_DATE'; Query OK, 0 rows affected (0.00 sec) mysql> Insert into year_testing(OrderDate) values('2017:00:00'); Query OK, 1 row ...
Read MoreHow MySQL use YEAR data type to store year value in a table?
MySQL permits to declare a column YEAR type, with the help of which we can store year values in that column.mysql> Create table year1 (Year_Copyright YEAR); Query OK, 0 rows affected (0.21 sec) mysql> Insert into year1(Year_Copyright) values (2017); Query OK, 1 row affected (0.08 sec) mysql> Select * from year1; +----------------+ | Year_Copyright | +----------------+ | 2017 | +----------------+ 1 row in set (0.00 sec)
Read MoreHow can we insert current year automatically in a YEAR type column of MySQL table?
It can be done by using either CURDATE() or NOW() in MySQL query as follows −mysql> Insert into year1(Year_Copyright) values (CURDATE()); Query OK, 1 row affected, 1 warning (0.06 sec) mysql> Select * from year1; +----------------+ | Year_Copyright | +----------------+ | 2017 | | 2017 | +----------------+ 2 rows in set (0.00 sec) mysql> Insert into year1(Year_Copyright) values (NOW()); Query OK, 1 row affected, 1 warning (0.06 sec) mysql> Select * from year1; +----------------+ | Year_Copyright | +----------------+ | 2017 | | 2017 | | 2017 | +----------------+ 1 rows in set (0.00 sec)
Read MoreIs there a naming convention for tables in MySQL?
No, MySQL does not have a preferred naming convention standard. If the name we have chosen is logical and consistent then it would be ok.Two major points need to be remembered, one is that no two tales/databases can have the same name and second we can choose any of the reserved words as the name of table/database.
Read MoreHow to get the first day of the current month in MySQL?
With the help of following MySQL query, we can get the first day of the current month −mysql> SELECT DATE_SUB(LAST_DAY(NOW()),INTERVAL DAY(LAST_DAY(NOW()))- 1 DAY) AS 'FIRST DAY OF CURRENT MONTH'; +----------------------------+ | FIRST DAY OF CURRENT MONTH | +----------------------------+ | 2017-10-01 | +----------------------------+ 1 row in set (0.00 sec)
Read MoreHow will addition, subtraction, multiplication and division operator work with date values stored in MySQL table?
When we try to do such kind of operations with date values stored in the table then MySQL is assuming the date values as the number and perform the arithmetic.Suppose we have a table named ‘example’ having a date value in ‘orderdate’ column then following arithmetic operation will clarify the above −mysql> select * from example; +------------+ | orderdate | +------------+ | 2017-05-25 | +------------+ 1 row in set (0.00 sec) mysql> select orderdate+10 from example; +--------------+ | orderdate+10 | +--------------+ | 20170535 | +--------------+ 1 row in set (0.00 sec) mysql> select orderdate*10 from example; ...
Read MoreHow can I check MySQL tables from a database in accordance with particularncolumn/s name?
The following statement shows the list of two tables having a column ‘email’ in Sample database −mysql> SELECT DISTINCT TABLE_NAME -> FROM INFORMATION_SCHEMA.COLUMNS -> WHERE COLUMN_NAME IN('EMAIL') -> AND TABLE_SCHEMA = 'SAMPLE'; +---------------+ | TABLE_NAME | +---------------+ | employee | | new_student | +---------------+ 2 rows in set (0.04 sec)
Read MoreWhat is the way to check the size of all the MySQL databases?
We can check the size of all MySQL databases with the help of the following statementmysql> SELECT table_schema "Database", -> SUM(data_length + index_length)/1024/1024 "Size in MB" -> FROM information_schema.TABLES GROUP BY table_schema; +--------------------+----------------+ | Database | Size in MB | +--------------------+----------------+ | gaurav | 1.04785156 | | information_schema | 0.00878906 | | mysql | 0.68551350 | | performance_schema | 0.00000000 | | sample | 0.04687500 | | tutorial | 0.03125000 | +--------------------+----------------+ 6 rows in set, 1 warning (0.33 sec)
Read MoreHow MySQL behaves when we use INTERVAL of time unit with CURDATE() function?
As we know that CURDATE() only returns the date unit so it would be ambiguous to use INTERVAL of time unit with CURDATE(). MySQL always represents current date with ‘00:00:00’ time hence when we use INTERVAL of time unit with CURDATE() then such kind of time arithmetic would take this time into consideration. Following examples will clarify it −mysql> Select CURDATE() + INTERVAL 0 hour; +-----------------------------+ | curdate() + Interval 0 hour | +-----------------------------+ | 2017-10-28 00:00:00 | +-----------------------------+ 1 row in set (0.00 sec) mysql> select CURDATE() + INTERVAL 1 hour; +-----------------------------+ | curdate() ...
Read MoreWhy I got output 0(Zero) on converting date like '1965-05-15' to TIMESTAMP?
As we know that with the help of MySQL UNIX_TIMESTAMP function, we can produce the number of seconds from given date/DateTime. But when we try to convert a date like ‘1965-05-15’ it would give 0(Zero) as output because the range of TIMESTAMP is between ‘1970-01-01 00:00:01’ to ‘2038-01-19 08:44:07’. Hence, the date values beyond TIMESTAMP range cannot be converted and will return 0 as output always.Examples are given below −mysql> Select UNIX_TIMESTAMP ('1965-05-15'); +----------------------------------------------+ | unix_timestamp('1965-05-15 05:04:30') | +----------------------------------------------+ | ...
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