mirror of
https://github.com/sqlite/sqlite.git
synced 2025-07-29 08:01:23 +03:00
Add experimental date and time functions based on julian day number. (CVS 1069)
FossilOrigin-Name: a6197e2075fdf9db862484255ac16b2855bbef0a
This commit is contained in:
drh
322
src/func.c
322
src/func.c
@ -16,13 +16,14 @@
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** sqliteRegisterBuildinFunctions() found at the bottom of the file.
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** All other code has file scope.
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**
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** $Id: func.c,v 1.26 2003/06/28 16:20:23 drh Exp $
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** $Id: func.c,v 1.27 2003/08/09 21:32:28 drh Exp $
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*/
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#include <ctype.h>
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#include <math.h>
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#include <stdlib.h>
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#include <assert.h>
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#include "sqliteInt.h"
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#include "os.h"
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/*
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** Implementation of the non-aggregate min() and max() functions
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@ -497,6 +498,312 @@ static void minMaxFinalize(sqlite_func *context){
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}
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}
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/****************************************************************************
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** Time and date functions.
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**
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** SQLite processes all times and dates as Julian Day numbers. The
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** dates and times are stored as the number of days since noon
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** in Greenwich on January 01, 4713 B.C. (a.k.a -4713-01-01 12:00:00)
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** This implement requires years to be expressed as a 4-digit number
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** which means that only dates between 0000-01-01 and 9999-12-31 can
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** be represented, even though julian day numbers allow a much wider
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** range of dates.
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**
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** The Gregorian calendar system is used for all dates and times,
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** even those that predate the Gregorian calendar. Historians often
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** use the Julian calendar for dates prior to 1582-10-15 and for some
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** dates afterwards, depending on locale. Beware of this difference.
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**
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** The conversion algorithms are implemented based on descriptions
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** in the following text:
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**
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** Jean Meeus
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** Astronomical Algorithms, 2nd Edition, 1998
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** ISBM 0-943396-61-1
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** Willmann-Bell, Inc
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** Richmond, Virginia (USA)
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*/
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#ifndef SQLITE_OMIT_DATETIME_FUNCS
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/*
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** Convert N digits from zDate into an integer. Return
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** -1 if zDate does not begin with N digits.
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*/
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static int getDigits(const char *zDate, int N){
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int val = 0;
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while( N-- ){
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if( !isdigit(*zDate) ) return -1;
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val = val*10 + *zDate - '0';
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zDate++;
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}
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return val;
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}
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/*
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** Parse dates of the form HH:MM:SS or HH:MM. Store the
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** result (in days) in *prJD.
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**
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** Return 1 if there is a parsing error and 0 on success.
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*/
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static int parseHhMmSs(const char *zDate, double *prJD){
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int h, m, s;
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h = getDigits(zDate, 2);
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if( h<0 || zDate[2]!=':' ) return 1;
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zDate += 3;
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m = getDigits(zDate, 2);
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if( m<0 || m>59 ) return 1;
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zDate += 2;
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if( *zDate==':' ){
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s = getDigits(&zDate[1], 2);
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if( s<0 || s>59 ) return 1;
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zDate += 3;
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}else{
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s = 0;
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}
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while( isspace(*zDate) ){ zDate++; }
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*prJD = (h*3600.0 + m*60.0 + s)/86400.0;
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return 0;
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}
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/*
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** Parse dates of the form
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**
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** YYYY-MM-DD HH:MM:SS
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** YYYY-MM-DD HH:MM
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** YYYY-MM-DD
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**
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** Write the result as a julian day number in *prJD. Return 0
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** on success and 1 if the input string is not a well-formed
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** date.
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*/
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static int parseYyyyMmDd(const char *zDate, double *prJD){
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int Y, M, D;
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double rTime;
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int A, B, X1, X2;
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Y = getDigits(zDate, 4);
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if( Y<0 || zDate[4]!='-' ) return 1;
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zDate += 5;
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M = getDigits(zDate, 2);
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if( M<=0 || M>12 || zDate[2]!='-' ) return 1;
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zDate += 3;
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D = getDigits(zDate, 2);
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if( D<=0 || D>31 ) return 1;
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zDate += 2;
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while( isspace(*zDate) ){ zDate++; }
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if( isdigit(*zDate) ){
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if( parseHhMmSs(zDate, &rTime) ) return 1;
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}else if( *zDate==0 ){
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rTime = 0.0;
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}else{
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return 1;
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}
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/* The year, month, and day are now stored in Y, M, and D. Convert
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** these into the Julian Day number. See Meeus page 61.
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*/
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if( M<=2 ){
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Y--;
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M += 12;
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}
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A = Y/100;
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B = 2 - A + (A/4);
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X1 = 365.25*(Y+4716);
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X2 = 30.6001*(M+1);
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*prJD = X1 + X2 + D + B - 1524.5 + rTime;
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return 0;
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}
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/*
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** Attempt to parse the given string into a Julian Day Number. Return
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** the number of errors.
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**
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** The following are acceptable forms for the input string:
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**
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** YYYY-MM-DD
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** YYYY-MM-DD HH:MM
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** YYYY-MM-DD HH:MM:SS
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** HH:MM
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** HH:MM:SS
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** DDDD.DD
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** now
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*/
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static int parseDateOrTime(const char *zDate, double *prJD){
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int i;
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for(i=0; isdigit(zDate[i]); i++){}
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if( i==4 && zDate[i]=='-' ){
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return parseYyyyMmDd(zDate, prJD);
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}else if( i==2 && zDate[i]==':' ){
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return parseHhMmSs(zDate, prJD);
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}else if( i==0 && sqliteStrICmp(zDate,"now")==0 ){
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return sqliteOsCurrentTime(prJD);
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}else if( sqliteIsNumber(zDate) ){
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*prJD = atof(zDate);
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return 0;
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}
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return 1;
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}
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/*
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** Break up a julian day number into year, month, day, and seconds.
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** This function assume the Gregorian calendar - even for dates prior
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** to the invention of the Gregorian calendar in 1582.
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**
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** See Meeus page 63.
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*/
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static void decomposeDate(double JD, int *pY, int *pM, int *pD, int *pS){
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int Z, A, B, C, D, E, X1;
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Z = JD + 0.5;
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A = (Z - 1867216.25)/36524.25;
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A = Z + 1 + A - (A/4);
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B = A + 1524;
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C = (B - 122.1)/365.25;
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D = 365.25*C;
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E = (B-D)/30.6001;
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X1 = 30.6001*E;
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*pD = B - D - X1;
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*pM = E<14 ? E-1 : E-13;
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*pY = *pD>2 ? C - 4716 : C - 4715;
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*pS = (JD + 0.5 - Z)*86400.0;
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}
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/*
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** Check to see that all arguments are valid date strings. If any is
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** not a valid date string, return 0. If all are valid, return 1.
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** Write into *prJD the sum of the julian day numbers for all date
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** strings.
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*/
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static int isDate(
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sqlite_func *context,
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int argc,
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const char **argv,
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double *prJD
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){
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double r;
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int i;
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*prJD = 0.0;
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for(i=0; i<argc; i++){
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if( argv[i]==0 ) return 0;
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if( parseDateOrTime(argv[i], &r) ) return 0;
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*prJD += r;
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}
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return 1;
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}
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/*
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** The following routines implement the various date and time functions
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** of SQLite.
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*/
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static void juliandayFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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sqlite_set_result_double(context, JD);
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}
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}
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static void timestampFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, h, m, s;
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char zBuf[100];
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decomposeDate(JD, &Y, &M, &D, &s);
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h = s/3600;
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s -= h*3600;
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m = s/60;
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s -= m*60;
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sprintf(zBuf, "%04d-%02d-%02d %02d:%02d:%02d", Y, M, D, h, m, s);
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sqlite_set_result_string(context, zBuf, -1);
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}
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}
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static void timeFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, h, m, s;
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char zBuf[100];
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decomposeDate(JD, &Y, &M, &D, &s);
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h = s/3600;
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s -= h*3600;
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m = s/60;
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s -= m*60;
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sprintf(zBuf, "%02d:%02d:%02d", h, m, s);
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sqlite_set_result_string(context, zBuf, -1);
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}
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}
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static void dateFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, s;
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char zBuf[100];
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decomposeDate(JD, &Y, &M, &D, &s);
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sprintf(zBuf, "%04d-%02d-%02d", Y, M, D);
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sqlite_set_result_string(context, zBuf, -1);
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}
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}
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static void yearFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, s;
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decomposeDate(JD, &Y, &M, &D, &s);
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sqlite_set_result_int(context, Y);
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}
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}
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static void monthFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, s;
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decomposeDate(JD, &Y, &M, &D, &s);
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sqlite_set_result_int(context, M);
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}
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}
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static void dayofweekFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Z = JD + 1.5;
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sqlite_set_result_int(context, Z % 7);
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}
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}
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static void dayofmonthFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, s;
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decomposeDate(JD, &Y, &M, &D, &s);
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sqlite_set_result_int(context, D);
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}
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}
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static void secondFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, h, m, s;
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decomposeDate(JD, &Y, &M, &D, &s);
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h = s/3600;
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s -= h*3600;
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m = s/60;
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s -= m*60;
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sqlite_set_result_int(context, s);
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}
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}
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static void minuteFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, h, m, s;
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decomposeDate(JD, &Y, &M, &D, &s);
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h = s/3600;
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s -= h*3600;
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m = s/60;
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sqlite_set_result_int(context, m);
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}
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}
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static void hourFunc(sqlite_func *context, int argc, const char **argv){
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double JD;
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if( isDate(context, argc, argv, &JD) ){
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int Y, M, D, h, s;
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decomposeDate(JD, &Y, &M, &D, &s);
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h = s/3600;
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sqlite_set_result_int(context, h);
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}
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}
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#endif /* !defined(SQLITE_OMIT_DATETIME_FUNCS) */
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/***************************************************************************/
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/*
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** This function registered all of the above C functions as SQL
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** functions. This should be the only routine in this file with
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@ -529,6 +836,19 @@ void sqliteRegisterBuiltinFunctions(sqlite *db){
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{ "glob", 2, SQLITE_NUMERIC, globFunc },
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{ "nullif", 2, SQLITE_ARGS, nullifFunc },
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{ "sqlite_version",0,SQLITE_TEXT, versionFunc},
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#ifndef SQLITE_OMIT_DATETIME_FUNCS
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{ "julianday", -1, SQLITE_NUMERIC, juliandayFunc },
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{ "timestamp", -1, SQLITE_TEXT, timestampFunc },
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{ "time", -1, SQLITE_TEXT, timeFunc },
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{ "date", -1, SQLITE_TEXT, dateFunc },
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{ "year", -1, SQLITE_NUMERIC, yearFunc },
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{ "month", -1, SQLITE_NUMERIC, monthFunc },
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{ "dayofmonth",-1, SQLITE_NUMERIC, dayofmonthFunc },
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{ "dayofweek", -1, SQLITE_NUMERIC, dayofweekFunc },
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{ "hour", -1, SQLITE_NUMERIC, hourFunc },
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{ "minute", -1, SQLITE_NUMERIC, minuteFunc },
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{ "second", -1, SQLITE_NUMERIC, secondFunc },
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#endif
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#ifdef SQLITE_SOUNDEX
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{ "soundex", 1, SQLITE_TEXT, soundexFunc},
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#endif
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15
src/os.c
15
src/os.c
@ -1597,3 +1597,18 @@ char *sqliteOsFullPathname(const char *zRelative){
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return zFull;
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#endif
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}
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/*
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** Find the current time (in Universal Coordinated Time). Write the
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** current time and date as a Julian Day number into *prNow and
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** return 0. Return 1 if the time and date cannot be found.
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*/
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int sqliteOsCurrentTime(double *prNow){
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#if OS_UNIX
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time_t t;
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time(&t);
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*prNow = t/86400.0 + 2440587.5;
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return 0;
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#endif
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return 1;
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}
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1
src/os.h
1
src/os.h
@ -171,6 +171,7 @@ int sqliteOsWriteLock(OsFile*);
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int sqliteOsUnlock(OsFile*);
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int sqliteOsRandomSeed(char*);
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int sqliteOsSleep(int ms);
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int sqliteOsCurrentTime(double*);
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void sqliteOsEnterMutex(void);
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void sqliteOsLeaveMutex(void);
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char *sqliteOsFullPathname(const char*);
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@ -11,7 +11,7 @@
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*************************************************************************
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** Internal interface definitions for SQLite.
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**
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** @(#) $Id: sqliteInt.h,v 1.195 2003/07/30 12:34:12 drh Exp $
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** @(#) $Id: sqliteInt.h,v 1.196 2003/08/09 21:32:28 drh Exp $
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*/
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#include "config.h"
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#include "sqlite.h"
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@ -87,6 +87,7 @@
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/* #define SQLITE_OMIT_AUTHORIZATION 1 */
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/* #define SQLITE_OMIT_INMEMORYDB 1 */
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/* #define SQLITE_OMIT_VACUUM 1 */
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/* #define SQLITE_OMIT_TIMEDATE_FUNCS 1 */
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/*
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** Integers of known sizes. These typedefs might change for architectures
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