Kingbasees plug-in KDB of Jincang database_ date_ function

1. kdb_date_function Introduce

kdb_date_function It's a compatible mysql database date Extension of correlation function .

You need to create extension kdb_date_function, When you don't need to drop extension kdb_date_function that will do .

2. date_add

date_add — Realize the addition of dates

grammar ：

date_add(ts timestamp, iv interval) return timestamp. date_add(tstz timestamptz, iv interval) return timestamptz.

describe ：

date_add Will come true timestamp or timestamptz And interval Perform the operation of addition .

Parameters ：

iv

Used in date addition operation interval Type values .

ts

Used in date addition operation timestamp Type values .

tstz

Used in date addition operation timestamptz Type values .

Return value ：

Return the specific date type value after calculation .

annotation ：

give an example ：

select date_add('2000-10-10'::timestamp,interval '1 year');
                date_add
--------------------------
Wed Oct 10 00:00:00 2001
(1 row)

select date_add('2010-10-10 12:00:00'::timestamp,interval '1 year 1 day 2 hour');
                date_add
--------------------------
Tue Oct 11 14:00:00 2011
(1 row)

3. dateadd

dateadd — Realize the addition of dates

grammar ：

dateadd(i_unit text, i_value numeric, i_date time) return time.

dateadd(i_unit text, i_value numeric, i_date timestamp) return timestamp.

dateadd(i_unit text, i_value numeric, i_date timestamptz) return timestamptz.

describe ：

Realization timestamp or timestamptz or time Type is added to the specified format .

Parameters ：

i_unit

Specify what to add i_value The format of .

i_value

Specify the quantity to add .

i_date

Specify the date to be added .

Return value ：

Return the specific date type value after calculation .

annotation ：

i_unit The value of can make 'second','minute','hour','day','week','month','year' etc. .

give an example ：

SELECT dateadd(year,9998,'0001-01-01 00:00:00'::timestamptz);
                   dateadd
------------------------------
 Fri Jan 01 00:00:00 9999 PST
(1 row)

SELECT dateadd(year,201,'1900-01-01 00:00:00'::timestamptz);
                   dateadd
------------------------------
 Sat Jan 01 00:00:00 2101 PST
(1 row)

SELECT dateadd(year,30,'1970-01-01 00:00:00'::timestamptz);
                   dateadd
------------------------------
 Sat Jan 01 00:00:00 2000 PST
(1 row)

SELECT dateadd(year,-9998,'9999-12-31 00:00:00'::timestamptz);
                   dateadd
------------------------------
 Mon Dec 31 00:00:00 0001 PST
(1 row)

SELECT dateadd(year,-100,'2000-12-31 00:00:00'::timestamptz);
                   dateadd
------------------------------
 Mon Dec 31 00:00:00 1900 PST
(1 row)

SELECT dateadd(year,-34,'2004-12-31 00:00:00'::timestamptz);
                   dateadd
------------------------------
 Thu Dec 31 00:00:00 1970 PST
(1 row)

4. datediff

Compare the difference between the two dates

grammar ：

datediff(d1 date, d2 date) return integer. datediff(t text, d1 date, d2 date) return int8. datediff(t text, d1 time, d2 time) return int8. datediff(t text, d1 timetz, d2 timetz) return int8. datediff(t text, d1 timestamp, d2 timestamp) return int8. datediff(t text, d1 timestamptz, d2 timestamptz) return int8.

describe ：

Compare the specified... Between two dates text（ If this parameter exists ） The format gap .

Parameters ：

t

The format of the specified date gap to be returned .

d1,d2

Two date values for comparison .

Return value ：

return text Integer value in the format specified by type .

annotation ：

t The value of can make 'second','minute','hour','day','week','month','year' etc. .

give an example ：

SELECT datediff('year','0001-01-01'::date,'9999-12-31'::date);
 datediff
----------
         9998
(1 row)

SELECT datediff('year','1900-01-01 00:00:00'::date,'2000-12-31 00:00:00'::date);
 datediff
----------
          100
(1 row)

SELECT datediff(month,'0001-01-01 00:00:00'::date,'9999-12-31 00:00:00'::date);
 datediff
----------
   119987
(1 row)

SELECT datediff(month,'1900-01-01 00:00:00'::date,'2000-12-31 00:00:00'::date);
 datediff
----------
         1211
(1 row)

SELECT datediff('month','0001-01-01 00:00:00'::date,'9999-12-31 00:00:00'::date);
 datediff
----------
   119987
(1 row)

SELECT datediff('month','1900-01-01 00:00:00'::date,'2000-12-31 00:00:00'::date);
 datediff
----------
         1211
(1 row)

5. date_format

Get the specified format value of the specified date .

grammar ：

date_format(d timestamp, t text) return text. date_format(d timestamptz, t text) return text.

describe ：

Return date type value text Specified format .

Parameters ：

t

Specifies the format of the date to return .

d

Value of target format .

Return value ：

return text designated text Type value .

annotation ：

t The value of can be nls_date_format All values of type .

give an example ：

select date_format('2000-10-10 12:00:00','mm-yyyy-dd hh24:mi:ss');
         date_format
---------------------
 10-2000-10 12:00:00
(1 row)