Type Conversion Functions(1)

• cash_words(money)

  Description: Type conversion function, which converts money into text.

  Example:

  MogDB=# SELECT cash_words('1.23');
              cash_words
  -----------------------------------
   One dollar and twenty three cents
  (1 row)

• cast(x as y)

  Description: Converts x into the type specified by y.

  Example:

  MogDB=# SELECT cast('22-oct-1997' as timestamp);
        timestamp
  ---------------------
   1997-10-22 00:00:00
  (1 row)

• hextoraw(raw)

  Description: Converts a string in hexadecimal format into the raw type.

  Return type: raw

  Example:

  MogDB=# SELECT hextoraw('7D');
   hextoraw
  ----------
   7D
  (1 row)

• numtoday(numeric)

  Description: Converts values of the number type into the timestamp of the specified type.

  Return type: timestamp

  Example:

  MogDB=# SELECT numtoday(2);
   numtoday
  ----------
   2 days
  (1 row)

• pg_systimestamp()

  Description: Obtains the system timestamp.

  Return type: timestamp with time zone

  Example:

  MogDB=# SELECT pg_systimestamp();
          pg_systimestamp
  -------------------------------
   2015-10-14 11:21:28.317367+08
  (1 row)

• rawtohex(string)

  Description: Converts a string in binary format into hexadecimal format.

  The result is the ACSII code of the input characters in hexadecimal format.

  Return type: varchar

  Example:

  MogDB=# SELECT rawtohex('1234567');
      rawtohex
  ----------------
   31323334353637
  (1 row)

• to_bigint(varchar)

  Description: Converts the character type to the bigint type.

  Return type: bigint

  Example:

  MogDB=# SELECT to_bigint('123364545554455');
      to_bigint
  ----------------
   123364545554455
  (1 row)

• to_char (datetime/interval [, fmt])

  Description: Converts a DATETIME or INTERVAL value of the DATE/TIMESTAMP/TIMESTAMP WITH TIME ZONE/TIMESTAMP WITH LOCAL TIME ZONE type into the TEXT type according to the format specified by fmt.

  • The optional parameter fmt allows for the following types: date, time, week, quarter, and century. Each type has a unique template. The templates can be combined together. Common templates include HH, MI, SS, YYYY, MM, and DD.
  • A template may have a modification word. FM is a common modification word and is used to suppress the preceding zero or the following blank spaces.
  • For TIMESTAMP WITH TIME ZONE, you can use TZH, TZM, TZD, TZR parameters in TO_CHAR to output time zone information.

  Return type: TEXT

  Example:

  MogDB=# SELECT to_char(current_timestamp,'HH12:MI:SS');
   to_char
  ----------
   10:19:26
  (1 row)

  MogDB=# SELECT to_char(current_timestamp,'FMHH12:FMMI:FMSS');
   to_char
  ----------
   10:19:46
  (1 row)

  MogDB=# select to_char(systimestamp, 'TZH'); 
  to_char
  --------- 
  +08
  (1 row)
  
  MogDB=# select to_char(systimestamp, 'TZM');
  to_char
  ---------
  00
  (1 row)
  
  MogDB=# select to_char(systimestamp, 'TZD');
  to_char
  ---------
  CST
  (1 row)
  
  MogDB=# select to_char(systimestamp, 'TZR');
  to_char
  ---------------
  Asia/Shanghai
  (1 row)

  Table 1 Template Patterns for Date/Time Formatting

  Pattern	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)
  MS	millisecond (000-999)
  US	microsecond (000000-999999)
  SSSS	seconds past midnight (0-86399)
  AM, am, PM or pm	meridiem indicator (without periods)
  A.M., a.m., P.M. or p.m.	meridiem indicator (with periods)
  Y,YYY	year (4 or more digits) with comma
  YYYY	year (4 or more digits)
  YYY	last 3 digits of year
  YY	last 2 digits of year
  Y	last digit of year
  IYYY	ISO 8601 week-numbering year (4 or more digits)
  IYY	last 3 digits of ISO 8601 week-numbering year
  IY	last 2 digits of ISO 8601 week-numbering year
  I	last digit of ISO 8601 week-numbering year
  BC, bc, AD or ad	era indicator (without periods)
  B.C., b.c., A.D. or a.d.	era indicator (with periods)
  MONTH	full upper case month name (blank-padded to 9 chars)
  Month	full capitalized month name (blank-padded to 9 chars)
  month	full lower case month name (blank-padded to 9 chars)
  MON	abbreviated upper case month name (3 chars in English, localized lengths vary)
  Mon	abbreviated capitalized month name (3 chars in English, localized lengths vary)
  mon	abbreviated lower case month name (3 chars in English, localized lengths vary)
  MM	month number (01-12)
  DAY	full upper case day name (blank-padded to 9 chars)
  Day	full capitalized day name (blank-padded to 9 chars)
  day	full lower case day name (blank-padded to 9 chars)
  DY	abbreviated upper case day name (3 chars in English, localized lengths vary)
  Dy	abbreviated capitalized day name (3 chars in English, localized lengths vary)
  dy	abbreviated lower case day name (3 chars in English, localized lengths vary)
  DDD	day of year (001-366)
  IDDD	day of ISO 8601 week-numbering year (001-371; day 1 of the year is Monday of the first ISO week)
  DD	day of month (01-31)
  D	day of the week, Sunday (1) to Saturday (7)
  ID	ISO 8601 day of the week, Monday (1) to Sunday (7)
  W	week of month (1-5) (the first week starts on the first day of the month)
  WW	week number of year (1-53) (the first week starts on the first day of the year)
  IW	week number of ISO 8601 week-numbering year (01-53; the first Thursday of the year is in week 1)
  CC	century (2 digits) (the twenty-first century starts on 2001-01-01)
  J	Julian Day (integer days since November 24, 4714 BC at midnight UTC)
  Q	quarter
  RM	month in upper case Roman numerals (I-XII; I=January)
  rm	month in lower case Roman numerals (i-xii; i=January)
  TZ	upper case time-zone abbreviation (only supported in to_char)
  tz	lower case time-zone abbreviation (only supported in to_char)
  TZH	Time zone hour
  TZM	Time zone minute
  TZD	Time zone daylight saving time
  TZR	Time zone region

• to_char(double precision/real, text)

  Description: Converts the values of the floating point type into the strings in the specified format.

  Return type: text

  Example:

  MogDB=# SELECT to_char(125.8::real, '999D99');
   to_char
  ---------
    125.80
  (1 row)

• to_char (numeric/smallint/integer/bigint/double precision/real[, fmt])

  Descriptions: Converts an integer or a value in floating point format into a string in specified format.

  • The optional parameter fmt allows for the following types: decimal characters, grouping characters, positive/negative sign and currency sign. Each type has a unique template. The templates can be combined together. Common templates include: 9, 0, millesimal sign (,), and decimal point (.).
  • A template can have a modification word, similar to FM. However, FM does not suppress 0 which is output according to the template.
  • Use the template X or x to convert an integer value into a string in hexadecimal format.

  Return type: varchar

  Example:

  MogDB=# SELECT to_char(1485,'9,999');
   to_char
  ---------
    1,485
  (1 row)

  MogDB=# SELECT to_char( 1148.5,'9,999.999');
    to_char
  ------------
    1,148.500
  (1 row)

  MogDB=# SELECT to_char(148.5,'990999.909');
     to_char
  -------------
      0148.500
  (1 row)

  MogDB=# SELECT to_char(123,'XXX');
   to_char
  ---------
     7B
  (1 row)

• to_char(interval, text)

  Description: Converts the values of the time interval type into the strings in the specified format.

  Return type: text

  Example:

  MogDB=# SELECT to_char(interval '15h 2m 12s', 'HH24:MI:SS');
   to_char
  ----------
   15:02:12
  (1 row)

• to_char(int, text)

  Description: Converts the values of the integer type into the strings in the specified format.

  Return type: text

  Example:

  MogDB=# SELECT to_char(125, '999');
   to_char
  ---------
    125
  (1 row)

• to_char(set)

  Description: Converts the values of the SET type into the strings in the specified format.

  Return type: text

  Example:

  - The site column is of the SET type in the employee table.
     
  MogDB=# select to_char(site) from employee;
  to_char
  ---------
  beijing,nanjing
  beijing,wuhan
  (2 rows)

• to_char(numeric, text)

  Description: Converts the values of the numeric type into the strings in the specified format.

  Return type: text

  Example:

  MogDB=# SELECT to_char(-125.8, '999D99S');
   to_char
  ---------
   125.80-
  (1 row)

• to_char (string)

  Description: Converts the CHAR/VARCHAR/VARCHAR2/CLOB type into the VARCHAR type.

  If this function is used to convert data of the CLOB type, and the value to be converted exceeds the value range of the target type, an error is returned.

  Return type: varchar

  Example:

  MogDB=# SELECT to_char('01110');
   to_char
  ---------
   01110
  (1 row)

• to_char(timestamp, text)

  Description: Converts the values of the timestamp type into the strings in the specified format.

  Return type: text

  Example:

  MogDB=# SELECT to_char(current_timestamp, 'HH12:MI:SS');
   to_char
  ----------
   10:55:59
  (1 row)

• to_clob(char/nchar/varchar/varchar2/nvarchar/nvarchar2/text/raw)

  Description: Converts the raw type or text character set type CHAR, NCHAR, VARCHAR, VARCHAR2, NVARCHAR, NVARCHAR2, or TEXT to the CLOB type.

  Return type: clob

  Example:

  MogDB=# SELECT to_clob('ABCDEF'::RAW(10));
   to_clob
  ---------
   ABCDEF
  (1 row)

  MogDB=# SELECT to_clob('hello111'::CHAR(15));
   to_clob
  ----------
   hello111
  (1 row)

  MogDB=# SELECT to_clob('gauss123'::NCHAR(10));
   to_clob
  ----------
   gauss123
  (1 row)

  MogDB=# SELECT to_clob('gauss234'::VARCHAR(10));
   to_clob
  ----------
   gauss234
  (1 row)

  MogDB=# SELECT to_clob('gauss345'::VARCHAR2(10));
   to_clob
  ----------
   gauss345
  (1 row)

  MogDB=# SELECT to_clob('gauss456'::NVARCHAR2(10));
   to_clob
  ----------
   gauss456
  (1 row)

  MogDB=# SELECT to_clob('World222!'::TEXT);
    to_clob
  -----------
   World222!
  (1 row)

• to_date(text)

  Description: Converts values of the text type into the timestamp in the specified format. Currently, only the following two formats are supported:

  • Format 1: Date without separators, for example, 20150814. The value must contain the complete year, month, and day.
  • Format 2: Date with separators, for example, 2014-08-14. The separator can be any non-digit character.

  Return type: timestamp without time zone

  Example:

    MogDB=# SELECT to_date('2015-08-14');
           to_date
    ---------------------
     2015-08-14 00:00:00
    (1 row)

• to_date(text, text)

  Description: Converts the values of the string type into the dates in the specified format.

  Return type: timestamp without time zone

  Example:

  MogDB=# SELECT to_date('05 Dec 2000', 'DD Mon YYYY');
         to_date
  ---------------------
   2000-12-05 00:00:00
  (1 row)

• to_number ( expr [, fmt])

  Description: Converts expr into a value of the NUMBER type according to the specified format.

  For details about the type conversion formats, see Table 2.

  If a hexadecimal string is converted into a decimal number, the hexadecimal string can include a maximum of 16 bytes if it is to be converted into a sign-free number.

  During the conversion from a hexadecimal string to a decimal digit, the format string cannot have a character other than x or X. Otherwise, an error is reported.

  Return type: number

  Example:

  MogDB=# SELECT to_number('12,454.8-', '99G999D9S');
   to_number
  -----------
    -12454.8
  (1 row)

• to_number(text, text)

  Description: Converts the values of the string type into the numbers in the specified format.

  Return type: numeric

  Example:

  MogDB=# SELECT to_number('12,454.8-', '99G999D9S');
   to_number
  -----------
    -12454.8
  (1 row)

• to_timestamp(double precision)

  Description: Converts a UNIX century into a timestamp.

  Return type: timestamp with time zone

  Example:

  MogDB=# SELECT to_timestamp(1284352323);
        to_timestamp
  ------------------------
   2010-09-13 12:32:03+08
  (1 row)

• to_timestamp(string [,fmt])

  Description: Converts a string into a value of the timestamp type according to the format specified by fmt. When fmt is not specified, perform the conversion according to the format specified by nls_timestamp_format.

  In to_timestamp in MogDB,

  • If the input year YYYY is 0, an error will be reported.
  • If the input year YYYY is less than 0, specify SYYYY in fmt. The year with the value of n (an absolute value) BC will be output correctly.

  Characters in the fmt must match the schema for formatting the data and time. Otherwise, an error is reported.

  Return type: timestamp without time zone

  Example:

  MogDB=# SHOW nls_timestamp_format;
      nls_timestamp_format
  ----------------------------
   DD-Mon-YYYY HH:MI:SS.FF AM
  (1 row)
  
  MogDB=# SELECT to_timestamp('12-sep-2014');
      to_timestamp
  ---------------------
   2014-09-12 00:00:00
  (1 row)

  MogDB=# SELECT to_timestamp('12-Sep-10 14:10:10.123000','DD-Mon-YY HH24:MI:SS.FF');
        to_timestamp
  -------------------------
   2010-09-12 14:10:10.123
  (1 row)

  MogDB=# SELECT to_timestamp('-1','SYYYY');
        to_timestamp
  ------------------------
   0001-01-01 00:00:00 BC
  (1 row)

  MogDB=# SELECT to_timestamp('98','RR');
      to_timestamp
  ---------------------
   1998-01-01 00:00:00
  (1 row)

  MogDB=# SELECT to_timestamp('01','RR');
      to_timestamp
  ---------------------
   2001-01-01 00:00:00
  (1 row)

• to_timestamp(text, text)

  Description: Converts values of the string type into the timestamp of the specified type.

  Return type: timestamp

  Example:

  MogDB=# SELECT to_timestamp('05 Dec 2000', 'DD Mon YYYY');
      to_timestamp
  ---------------------
   2000-12-05 00:00:00
  (1 row)

Table 2 Template patterns for numeric formatting

Pattern	Description
9	Value with specified digits
0	Values with leading zeros
Period (.)	Decimal point
Comma (,)	Group (thousand) separator
PR	Negative values in angle brackets
S	Sign anchored to number (uses locale)
L	Currency symbol (uses locale)
D	Decimal point (uses locale)
G	Group separator (uses locale)
MI	Minus sign in the specified position (if the number is less than 0)
PL	Plus sign in the specified position (if the number is greater than 0)
SG	Plus or minus sign in the specified position
RN	Roman numerals (the input values are between 1 and 3999)
TH or th	Ordinal number suffix
V	Shifts specified number of digits (decimal)

• abstime_text

  Description: Converts abstime to text.

  Parameter: abstime

  Return type: text

• abstime_to_smalldatetime

  Description: Converts abstime to smalldatatime.

  Parameter: abstime

  Return type: smalldatetime

• bigint_tid

  Description: Converts bigint to tid.

  Parameter: bigint

  Return type: tid

• bool_int1

  Description: Converts bool to int1.

  Parameter: Boolean

  Return type: tinyint

• bool_int2

  Description: Converts bool to int2.

  Parameter: Boolean

  Return type: smallint

• bool_int8

  Description: Converts bool to int8.

  Parameter: Boolean

  Return type: bigint

• bpchar_date

  Description: Converts a string to a date.

  Parameter: character

  Return type: date

• bpchar_float4

  Description: Converts a string to float4.

  Parameter: character

  Return type: real

• bpchar_float8

  Description: Converts a string to float8.

  Parameter: character

  Return type: double precision

• bpchar_int4

  Description: Converts a string to int4.

  Parameter: character

  Return type: integer