String Functions and Operators

str	String
str[i]	String indexing.
str[from:to]	String slicing.
str ++ str	String concatenation.
str like pattern	Case-sensitive simple string matching.
str ilike pattern	Case-insensitive simple string matching.
= != ?= ?!= < > <= >=	Comparison operators
to_str()	Returns the string representation of the input value.
len()	Returns a string’s length.
contains()	Tests if a string contains a substring.
find()	Finds the index of a substring.
str_lower()	Returns a lowercase copy of the input string.
str_upper()	Returns an uppercase copy of the input string.
str_title()	Returns a titlecase copy of the input string.
str_pad_start()	Returns the input string padded at the start to the length n.
str_pad_end()	Returns the input string padded at the end to the length n.
str_trim()	Returns the input string with trim characters removed from both ends.
str_trim_start()	Returns the input string with all trim characters removed from the start.
str_trim_end()	Returns the input string with all trim characters removed from the end.
str_repeat()	Repeats the input string n times.
str_replace()	Replaces all occurrences of a substring with a new one.
str_reverse()	Reverses the order of the characters in the string.
str_split()	Splits a string into an array using a delimiter.
re_match()	Finds the first regular expression match in a string.
re_match_all()	Finds all regular expression matches in a string.
re_replace()	Replaces matching substrings in a given string.
re_test()	Tests if a regular expression has a match in a string.

type

str

A unicode string of text.

Any other type (except bytes) can be cast to and from a string:

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select <str>42;

{'42'}

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select <bool>'true';

{true}

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select "I ❤️ EdgeDB";

{'I ❤️ EdgeDB'}

Note that when a str is cast into a json, the result is a JSON string value. The same applies for casting back from json - only a JSON string value can be cast into a str:

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select <json>'Hello, world';

{'"Hello, world"'}

There are two kinds of string literals in EdgeQL: regular and raw. Raw string literals do not evaluate \, so \n in in a raw string is two characters \ and n.

The regular string literal syntax is 'a string' or a "a string". Two raw string syntaxes are illustrated below:

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select r'A raw \n string';

{'A raw \\n string'}

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select 'Not a raw \n string';

{
  'Not a raw
 string',
}

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select $$something$$;

{'something'}

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...

select $marker$something $$
nested \!$$$marker$;

{'something $$
nested \!$$'}

Regular strings use \ to indicate line continuation. When a line continuation symbol is encountered, the symbol itself as well as all the whitespace characters up to the next non-whitespace character are omitted from the string:

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db> 
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select 'Hello, \
        world';

{'"Hello, world"'}

This type is subject to the Postgres maximum field size of 1GB.

operator

str[i]

str [ int64 ] -> str

String indexing.

Indexing starts at 0. Negative indexes are also valid and count from the end of the string.

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select 'some text'[1];

{'o'}

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select 'some text'[-1];

{'t'}

It is an error to attempt to extract a character at an index outside the bounds of the string:

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select 'some text'[8];

{'t'}

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select 'some text'[9];

InvalidValueError: string index 9 is out of bounds

A slice up to the next index can be used if an empty string is preferred to an error when outside the bounds of the string:

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select 'some text'[8:9];

{'t'}

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select 'some text'[9:10];

{''}

operator

str[from:to]

str [ int64 : int64 ] -> str

String slicing.

Indexing starts at 0. Negative indexes are also valid and count from the end of the string.

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select 'some text'[1:3];

{'om'}

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select 'some text'[-4:];

{'text'}

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select 'some text'[:-5];

{'some'}

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select 'some text'[5:-2];

{'te'}

It is perfectly acceptable to use indexes outside the bounds of a string in a slice:

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select 'some text'[-4:100];

{'text'}

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select 'some text'[-100:-5];

{'some'}

operator

str ++ str

str ++ str -> str

String concatenation.

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select 'some' ++ ' text';

{'some text'}

operator

str like pattern

str like str -> boolstr not like str -> bool

Case-sensitive simple string matching.

Returns true if the value (the str on the left) matches the pattern (the str on the right) and false otherwise. The operator not like is the negation of like.

The pattern matching rules are as follows:

pattern	interpretation
`%`	matches zero or more characters
`_`	matches exactly one character
`\%`	matches a literal “%”
`\_`	matches a literal “_”
any other character	matches itself

In particular, this means that if there are no special symbols in the pattern, the operators like and not like work identical to = and !=, respectively.

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select 'abc' like 'abc';

{true}

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select 'abc' like 'a%';

{true}

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select 'abc' like '_b_';

{true}

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select 'abc' like 'c';

{false}

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select 'a%%c' not like r'a\%c';

{true}

operator

str ilike pattern

str ilike str -> boolstr not ilike str -> bool

Case-insensitive simple string matching.

The operators ilike and not ilike work the same way as like and not like, except that the pattern is matched in a case-insensitive manner.

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select 'Abc' ilike 'a%';

{true}

function

str_lower()

std::str_lower(string: str) -> str

Returns a lowercase copy of the input string.

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select str_lower('Some Fancy Title');

{'some fancy title'}

function

str_upper()

std::str_upper(string: str) -> str

Returns an uppercase copy of the input string.

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select str_upper('Some Fancy Title');

{'SOME FANCY TITLE'}

function

str_title()

std::str_title(string: str) -> str

Returns a titlecase copy of the input string.

Every word in the string will have the first letter capitalized and the rest converted to lowercase.

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select str_title('sOmE fAnCy TiTlE');

{'Some Fancy Title'}

function

str_pad_start()

std::str_pad_start(string: str, n: int64, fill: str = ' ') -> str

Returns the input string padded at the start to the length n.

If the string is longer than n, then it is truncated to the first n characters. Otherwise, the string is padded on the left up to the total length n using fill characters (space by default).

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select str_pad_start('short', 10);

{'     short'}

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select str_pad_start('much too long', 10);

{'much too l'}

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select str_pad_start('short', 10, '.:');

{'.:.:.short'}

function

str_pad_end()

std::str_pad_end(string: str, n: int64, fill: str = ' ') -> str

Returns the input string padded at the end to the length n.

If the string is longer than n, then it is truncated to the first n characters. Otherwise, the string is padded on the right up to the total length n using fill characters (space by default).

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select str_pad_end('short', 10);

{'short     '}

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select str_pad_end('much too long', 10);

{'much too l'}

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select str_pad_end('short', 10, '.:');

{'short.:.:.'}

function

str_trim_start()

std::str_trim_start(string: str, trim: str = ' ') -> str

Returns the input string with all trim characters removed from the start.

If trim specifies more than one character they will be removed from the beginning of the string regardless of the order in which they appear.

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select str_trim_start('     data');

{'data'}

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select str_trim_start('.....data', '.:');

{'data'}

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select str_trim_start(':::::data', '.:');

{'data'}

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select str_trim_start(':...:data', '.:');

{'data'}

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select str_trim_start('.:.:.data', '.:');

{'data'}

function

str_trim_end()

std::str_trim_end(string: str, trim: str = ' ') -> str

Returns the input string with all trim characters removed from the end.

If trim specifies more than one character they will be removed from the end of the string regardless of the order in which they appear.

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select str_trim_end('data     ');

{'data'}

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select str_trim_end('data.....', '.:');

{'data'}

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select str_trim_end('data:::::', '.:');

{'data'}

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select str_trim_end('data:...:', '.:');

{'data'}

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select str_trim_end('data.:.:.', '.:');

{'data'}

function

str_trim()

std::str_trim(string: str, trim: str = ' ') -> str

Returns the input string with trim characters removed from both ends.

If trim specifies more than one character they will be removed from both ends of the string regardless of the order in which they appear. This is the same as applying str_trim_start() and str_trim_end().

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select str_trim('  data     ');

{'data'}

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select str_trim('::data.....', '.:');

{'data'}

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select str_trim('..data:::::', '.:');

{'data'}

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select str_trim('.:data:...:', '.:');

{'data'}

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select str_trim(':.:.data.:.', '.:');

{'data'}

function

str_repeat()

std::str_repeat(string: str, n: int64) -> str

Repeats the input string n times.

An empty string is returned if n is zero or negative.

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select str_repeat('.', 3);

{'...'}

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select str_repeat('foo', -1);

{''}

function

str_replace()

std::str_replace(s: str, old: str, new: str) -> str

Replaces all occurrences of a substring with a new one.

Given a string s, finds all non-overlapping occurrences of the substring old and replaces them with the substring new.

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select str_replace('hello world', 'h', 'H');

{'Hello world'}

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select str_replace('hello world', 'l', '[L]');

{'he[L][L]o wor[L]d'}

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select str_replace('hello world', 'o', '😄');

{'hell😄 w😄rld'}

function

str_reverse()

std::str_reverse(string: str) -> str

Reverses the order of the characters in the string.

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select str_reverse('Hello world');

{'dlrow olleH'}

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select str_reverse('Hello 👋 world 😄');

{'😄 dlrow 👋 olleH'}

function

str_split()

std::str_split(s: str, delimiter: str) -> array<str>

Splits a string into array elements using the supplied delimiter.

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select str_split('1, 2, 3', ', ');

{['1', '2', '3']}

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select str_split('123', '');

{['1', '2', '3']}

function

re_match()

std::re_match(pattern: str, string: str) -> array<str>

Finds the first regular expression match in a string.

Given an input string and a regular expression pattern, finds the first match for the regular expression within the string. Each match returned is represented by an array<str> of matched groups.

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select re_match(r'\w{4}ql', 'I ❤️ edgeql');

{['edgeql']}

function

re_match_all()

std::re_match_all(pattern: str, string: str) -> set of array<str>

Finds all regular expression matches in a string.

Given an input string and a regular expression pattern, repeatedly matches the regular expression within the string. Returns the set of all matches, with each match represented by an array<str> of matched groups.

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select re_match_all(r'a\w+', 'an abstract concept');

{['an'], ['abstract']}

function

re_replace()

std::re_replace(pattern: str, sub: str, string: str, named only flags: str='') -> str

Replaces matching substrings in a given string.

Takes an input string and a regular expression pattern, replacing matching substrings with the replacement string sub. Optional flag arguments can be used to specify additional regular expression flags.

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select re_replace('a', 'A', 'Alabama');

{'AlAbama'}

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select re_replace('a', 'A', 'Alabama', flags := 'g');

{'AlAbAmA'}

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select re_replace('A', 'A', 'Alabama', flags := 'ig');

{'AlAbAmA'}

function

re_test()

std::re_test(pattern: str, string: str) -> bool

Tests if a regular expression has a match in a string.

Given an input string and a regular expression pattern, tests whether there is a match for the regular expression within the string. Returns true if there is a match, false otherwise.

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select re_test(r'a', 'abc');

{true}

function

to_str()

std::to_str(val: datetime, fmt: optional str={}) -> strstd::to_str(val: duration, fmt: optional str={}) -> strstd::to_str(val: int64, fmt: optional str={}) -> strstd::to_str(val: float64, fmt: optional str={}) -> strstd::to_str(val: bigint, fmt: optional str={}) -> strstd::to_str(val: decimal, fmt: optional str={}) -> strstd::to_str(val: json, fmt: optional str={}) -> strstd::to_str(val: bytes) -> strstd::to_str(val: cal::local_datetime, fmt: optional str={}) -> strstd::to_str(val: cal::local_date, fmt: optional str={}) -> strstd::to_str(val: cal::local_time, fmt: optional str={}) -> str

Returns the string representation of the input value.

A versatile polymorphic function defined for different input types, to_str uses corresponding converter functions from str to specific types via the format argument fmt.

When converting bytes, datetime, cal::local_datetime, cal::local_date, cal::local_time, duration this function is the inverse of to_bytes(), to_datetime(), cal::to_local_datetime(), cal::to_local_date(), cal::to_local_time(), to_duration(), correspondingly.

For valid date and time formatting patterns see here.

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db> 
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select to_str(<datetime>'2018-05-07 15:01:22.306916-05',
              'FMDDth "of" FMMonth, YYYY');

{'7th of May, 2018'}

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select to_str(<cal::local_date>'2018-05-07', 'CCth "century"');

{'21st century'}

If you want to use literal text in your format string, it’s best to enclose it in double quotes as shown above with of and century.

When converting one of the numeric types, this function is the reverse of: to_bigint(), to_decimal(), to_int16(), to_int32(), to_int64(), to_float32(), to_float64().

For valid number formatting patterns see here.

Regular Expressions

EdgeDB supports Regular expressions (REs), as defined in POSIX 1003.2. They come in two forms: BRE (basic RE) and ERE (extended RE). In addition, EdgeDB supports certain common extensions to the POSIX standard commonly known as ARE (advanced RE). More details about BRE, ERE, and ARE support can be found in PostgreSQL documentation.

The table below outlines the different options accepted as the flags argument to various regular expression functions, or as embedded options in the pattern itself, e.g. '(?i)fooBAR':

Option Flags

Option	Description
`b`	rest of RE is a BRE
`c`	case-sensitive matching (overrides operator type)
`e`	rest of RE is an ERE
`i`	case-insensitive matching (overrides operator type)
`m`	historical synonym for n
`n`	newline-sensitive matching
`p`	partial newline-sensitive matching
`q`	rest of RE is a literal (“quoted”) string, all ordinary characters
`s`	non-newline-sensitive matching (default)
`t`	tight syntax (default)
`w`	inverse partial newline-sensitive (“weird”) matching
`x`	expanded syntax ignoring whitespace characters

Formatting

Some of the type converter functions take an extra argument specifying formatting (either for converting to a str or parsing from one). The different formatting options are collected in this section.

Date and time formatting options

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_str()`)
tz	lower case time-zone abbreviation (only supported in `to_str()`)
TZH	time-zone hours
TZM	time-zone minutes
OF	time-zone offset from UTC (only supported in `to_str()`)

Some additional formatting modifiers:

Modifier	Description	Example
FM prefix	fill mode (suppress leading zeroes and padding blanks)	FMMonth
TH suffix	upper case ordinal number suffix	DDTH, e.g., 12TH
th suffix	lower case ordinal number suffix	DDth, e.g., 12th
FX prefix	fixed format global option (see usage notes)	FX Month DD Day

Whitespace is normally ignored when parsing string input, unless the FX prefix modifier is used. For example:

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db> 
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select cal::to_local_date(
    '2000    JUN', 'YYYY MON');

{<cal::local_date>'2000-06-01'}

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db> 
...

select cal::to_local_date(
    '2000    JUN', 'FXYYYY MON');

InternalServerError: invalid value "   " for "MON"

Ordinary text is allowed in to_str() format strings and will be output literally. For better compatibility you should put a plain substring in double quotes to force it to be interpreted as literal text even if it contains template patterns now or could in the future.

Number formatting options

Pattern	Description
9	digit position (can be dropped if insignificant)
0	digit position (will not be dropped even if insignificant)
.	(period) decimal point
,	(comma) group (thousands) separator
PR	negative value 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 specified position (if number < 0)
PL	plus sign in specified position (if number > 0)
SG	plus/minus sign in specified position
RN	Roman numeral (input between 1 and 3999)
TH or th	ordinal number suffix
V	shift specified number of digits (see notes)
EEEE	exponent for scientific notation

Some additional formatting modifiers:

Modifier	Description	Example
FM prefix	fill mode (suppress leading zeroes and padding blanks)	FM99.99
TH suffix	upper case ordinal number suffix	999TH
th suffix	lower case ordinal number suffix	999th

String Functions and Operators​

Regular Expressions​

Option Flags​

Formatting​

Date and time formatting options​

Number formatting options​

String Functions and Operators

Regular Expressions

Option Flags

Formatting

Date and time formatting options

Number formatting options