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Formatting Functions

Author: Written by Karel Zak on 2000-01-24.

The Postgres formatting functions provide a powerful set of tools for converting various datetypes (date/time, int, float, numeric) to formatted strings and for converting from formatted strings to specific datetypes.

Note: The second argument for all formatting functions is a template to be used for the conversion.

Table 5-7. Formatting Functions

Function Returns Description Example
to_char(timestamp, text) text convert timestamp to string to_char(timestamp 'now','HH12:MI:SS')
to_char(int, text) text convert int4/int8 to string to_char(125, '999')
to_char(float, text) text convert float4/float8 to string to_char(125.8, '999D9')
to_char(numeric, text) text convert numeric to string to_char(numeric '-125.8', '999D99S')
to_date(text, text) date convert string to date to_date('05 Dec 2000', 'DD Mon YYYY')
to_timestamp(text, text) date convert string to timestamp to_timestamp('05 Dec 2000', 'DD Mon YYYY')
to_number(text, text) numeric convert string to numeric to_number('12,454.8-', '99G999D9S')

Table 5-8. Templates for date/time conversions

Template Description
HH hour of day (01-12)
HH12 hour of day (01-12)
HH24 hour of day (00-23)
MI minute (00-59)
SS second (00-59)
SSSS seconds past midnight (0-86399)
AM or A.M. or PM or P.M. meridian indicator (upper case)
am or a.m. or pm or p.m. meridian indicator (lower case)
Y,YYY year (4 and more digits) with comma
YYYY year (4 and more digits)
YYY last 3 digits of year
YY last 2 digits of year
Y last digit of year
BC or B.C. or AD or A.D. year indicator (upper case)
bc or b.c. or ad or a.d. year indicator (lower case)
MONTH full upper case month name (9 chars)
Month full mixed case month name (9 chars)
month full lower case month name (9 chars)
MON upper case abbreviated month name (3 chars)
Mon abbreviated mixed case month name (3 chars)
mon abbreviated lower case month name (3 chars)
MM month (01-12)
DAY full upper case day name (9 chars)
Day full mixed case day name (9 chars)
day full lower case day name (9 chars)
DY abbreviated upper case day name (3 chars)
Dy abbreviated mixed case day name (3 chars)
dy abbreviated lower case day name (3 chars)
DDD day of year (001-366)
DD day of month (01-31)
D day of week (1-7; SUN=1)
W week of month
WW week number of year
CC century (2 digits)
J Julian Day (days since January 1, 4712 BC)
Q quarter
RM month in Roman Numerals (I-XII; I=JAN) - upper case
rm month in Roman Numerals (I-XII; I=JAN) - lower case

All templates allow the use of prefix and suffix modifiers. Modifiers are always valid for use in templates. The prefix 'FX' is a global modifier only.

Table 5-9. Suffixes for templates for date/time to_char()

Suffix Description Example
FM fill mode prefix FMMonth
TH upper ordinal number suffix DDTH
th lower ordinal number suffix DDTH
FX FiXed format global option (see below) FX Month DD Day
SP spell mode (not yet implemented) DDSP

Usage notes:

  • to_timestamp and to_date skip blank space if the FX option is not used. FX must be specified as the first item in the template.

  • Backslash ("\") must be specified with a double backslash ("\\"); for example '\\HH\\MI\\SS'.

  • A double quote ('"') between quotation marks is skipped and is not parsed. If you want to write a double quote to output you must preceed it with a double backslash ('\\"), for example '\\"YYYY Month\\"'.

  • to_char supports text without a leading double quote ('"'), but any string between a quotation marks is rapidly handled and you are guaranteed that it will not be interpreted as a template keyword (example: '"Hello Year: "YYYY').

Table 5-10. Templates for to_char(numeric)

Template Description
9 value with the specified number of digits
0 value with leading zeros
. (period) decimal point
, (comma) group (thousand) separator
PR negative value in angle brackets
S negative value with minus sign (use locales)
L currency symbol (use locales)
D decimal point (use locales)
G group separator (use locales)
MI minus sign on specified position (if number < 0)
PL plus sign on specified position (if number > 0)
SG plus/minus sign on specified position
RN roman numeral (input between 1 and 3999)
TH or th convert to ordinal number
V Shift n digits (see notes)
EEEE science numbers. Now not supported.

Usage notes:

  • A sign formatted using 'SG', 'PL' or 'MI' is not an anchor in the number; for example, to_char(-12, 'S9999') produces ' -12', but to_char(-12, 'MI9999') produces '- 12'. The Oracle implementation does not allow the use of MI ahead of 9, but rather requires that 9 preceeds MI.

  • PL, SG, and TH are Postgres extensions.

  • 9 specifies a value with the same number of digits as there are 9s. If a digit is not available use blank space.

  • TH does not convert values less than zero and does not convert decimal numbers. TH is a Postgres extension.

  • V effectively multiplies the input values by 10^n, where n is the number of digits following V. to_char does not support the use of V combined with a decimal point (e.g. "99.9V99" is not allowed).

Table 5-11. to_char Examples

Input Output
to_char(now(),'Day, HH12:MI:SS') 'Tuesday , 05:39:18'
to_char(now(),'FMDay, HH12:MI:SS') 'Tuesday, 05:39:18'
to_char(-0.1,'99.99') ' -.10'
to_char(-0.1,'FM9.99') '-.1'
to_char(0.1,'0.9') ' 0.1'
to_char(12,'9990999.9') ' 0012.0'
to_char(12,'FM9990999.9') '0012'
to_char(485,'999') ' 485'
to_char(-485,'999') '-485'
to_char(485,'9 9 9') ' 4 8 5'
to_char(1485,'9,999') ' 1,485'
to_char(1485,'9G999') ' 1 485'
to_char(148.5,'999.999') ' 148.500'
to_char(148.5,'999D999') ' 148,500'
to_char(3148.5,'9G999D999') ' 3 148,500'
to_char(-485,'999S') '485-'
to_char(-485,'999MI') '485-'
to_char(485,'999MI') '485'
to_char(485,'PL999') '+485'
to_char(485,'SG999') '+485'
to_char(-485,'SG999') '-485'
to_char(-485,'9SG99') '4-85'
to_char(-485,'999PR') '<485>'
to_char(485,'L999') 'DM 485
to_char(485,'RN') ' CDLXXXV'
to_char(485,'FMRN') 'CDLXXXV'
to_char(5.2,'FMRN') V
to_char(482,'999th') ' 482nd'
to_char(485, '"Good number:"999') 'Good number: 485'
to_char(485.8,'"Pre-decimal:"999" Post-decimal:" .999') 'Pre-decimal: 485 Post-decimal: .800'
to_char(12,'99V999') ' 12000'
to_char(12.4,'99V999') ' 12400'
to_char(12.45, '99V9') ' 125'