Day 43 – SQL Dates
In SQL, dates are a common data type used to represent specific points in time. SQL supports several date-related data types, including DATE, TIME, DATETIME, TIMESTAMP, and INTERVAL.
The DATE data type represents a specific calendar date, without any time zone information. The format for a DATE value is ‘YYYY-MM-DD’, where YYYY is the year, MM is the month (1-12), and DD is the day of the month.
The TIME data type represents a specific time of day, without any date or time zone information. The format for a TIME value is ‘HH:MM:SS’, where HH is the hour (0-23), MM is the minute (0-59), and SS is the second (0-59).
The DATETIME data type represents a specific date and time, without any time zone information. The format for a DATETIME value is ‘YYYY-MM-DD HH:MM:SS’, where YYYY is the year, MM is the month (1-12), DD is the day of the month, HH is the hour (0-23), MM is the minute (0-59), and SS is the second (0-59).
The TIMESTAMP data type is similar to the DATETIME data type, but it also includes time zone information. The format for a TIMESTAMP value is ‘YYYY-MM-DD HH:MM:SS.SSSSSS +HH:MM’, where the first part is the same as a DATETIME value, and the second part represents the time zone offset.
The INTERVAL data type represents a duration of time, such as a number of years, months, days, hours, minutes, or seconds. The format for an INTERVAL value is ‘interval value unit’, where interval value is a number and unit is a time unit, such as YEAR, MONTH, DAY, HOUR, MINUTE, or SECOND.
For example, let’s say we have a table named “orders” with columns “order_id”, “customer_id”, “order_date”, and “order_total”. We want to insert a new row into the table with an order date of March 30, 2023. The INSERT statement for this row would be as follows:
INSERT INTO orders (order_id, customer_id, order_date, order_total) VALUES (1, 123, '2023-03-30', 100.00);
In the above example, we have used the DATE data type to represent the order date as ‘2023-03-30’.
It is important to note that date and time values in SQL are subject to the rules of the underlying operating system and may vary depending on the database system being used. It is also important to ensure that date and time values are handled correctly when performing calculations or comparisons in SQL.