What are the Oracle date functions?

There are the following:

date, which contains the century, year, month, day, hour, minute, and second. Occupies 7 bytes, 1 byte for each part above.

Timestamp datetime can be included to the nearest decimal second.

Timestamp with Time Zone contains time zone information.

Timestamp with Local Time Zone contains the time zone information and is automatically adjusted.

is a relational database management system from Oracle. It is a product that has been leading the way in the field of databases. It can be said that Oracle database system is currently the world's most popular relational database management system, the system is portable, easy to use, strong functions, suitable for all kinds of large, medium, small and microcomputer environments.

It is an efficient, reliable database solution that adapts to high throughput.

It consists of at least one tablespace and database schema objects. Here, a schema is a collection of objects, and a schema object is a logical structure that directly references database data. Schema objects include structures like this:

Tables, views, sequences, stored procedures, synonyms, indexes, clusters, database chains, and more. The logical storage structure consists of tablespaces, segments, and scopes that describe how the physical space of the database is used.

In summary, a logical structure consists of a logical storage structure (tablespaces, segments, ranges, blocks) and a logical data structure (tables, views, sequences, stored procedures, synonyms, indexes, clusters, and database chains, etc.), in which the schema objects (logical data structures) and relationships form the relational design of the database.

Let's name a few.

Function]: Returns the current date.

Parameter]: No parameter, no parentheses.

Return]: Date.

Example: select sysdate hz from dual;

Return: 2016-05-7

n1) function]: Returns the new date after adding n1 month to date d1.

Parameters] :d 1, date type, n1 numeric type.

Return]: Date.

Example】select sysdate,add months(sysdate,3) hz from dual;

Return: 2016-05-7, 2016-08-7

Function]: Returns the date of the last day of the month in which the date d1 is located.

Parameters] :d 1, date type.

Return]: Date.

Example: select sysdate,last day(sysdate) hz from dual;

Return: 2016-05-7, 2016-05-31

d2) Function]: Returns the number of months between date d1 and date d2.

Parameters] :d 1, d2 date type.

Returns]: Number If d1>d2, a positive number is returned If d1 [Example] select sysdate, months between(sysdate,to date(.)'2006-01-01','yyyy-mm-dd')),months_between(sysdate,to_date('2016-01-01','yyyy-mm-dd')) from dual;

Return: 2014-06-29,

date contains.

Century, year, month, day, hour, minute, circle, second.

It is 7 bytes for the width of the main collapse, and 1 byte for each part of the upper part.

timestamp

Date & Time. Can be included down to fractional seconds.

timestamp

withtime

zone contains the information of the zone.

timestamp

withlocal

The timezone contains the time zone information and is automatically adjusted.

oracle query dates can be used with regression=

However, the data type must be the same on both sides of the equal sign, for example'2010-9-19'This is a string and cannot be directly compared to a field of the date class.

Date conversion is required:

1. Convert the date to a string.

to_char(date,'yyyy-mm-dd')=2009-09-19'

2. Convert strings to dates.

to_date('2009-9-19','yyyy-mm-dd')=trunc(date)

The date itself may have hours, minutes and seconds, so be careful.