String functions

String functions generally take strings as inputs and return strings as outputs.

Unless specified, all of the arguments and return types in the following table are strings and all indexes are 1-based. The 0 index is considered to be before the start of the string.

Function Definition Datatype constraint

x || y

Concatenation operator

x,y in {string, clob}, return type is string or character large object (CLOB).

ASCII(x)

Provide ASCII value of the left most character[1] in x. The empty string will as input will return null.

return type is integer

CHR(x) CHAR(x)

Provide the character[1] for ASCII value x [a].

x in {integer}

[1] For the engine’s implementations of the ASCII and CHR functions, characters are limited to UCS2 values only. For pushdown there is little consistency among sources for character values beyond character code 255.

CONCAT(x, y)

Concatenates x and y with ANSI semantics. If x and/or y is null, returns null.

x, y in {string}

CONCAT2(x, y)

Concatenates x and y with non-ANSI null semantics. If x and y is null, returns null. If only x or y is null, returns the other value.

x, y in {string}

ENDSWITH(x, y)

Checks if y ends with x. If x or y is null, returns null.

x, y in {string}, returns boolean

INITCAP(x)

Make first letter of each word in string x capital and all others lowercase.

x in {string}

INSERT(str1, start, length, str2)

Insert string2 into string1

str1 in {string}, start in {integer}, length in {integer}, str2 in {string}

LCASE(x)

Lowercase of x

x in {string}

LEFT(x, y)

Get left y characters of x

x in {string}, y in {integer}, return string

LENGTH(x) CHAR_LENGTH(x) CHARACTER_LENGTH(x)

Length of x

return type is integer

LOCATE(x, y) POSITION(x IN y)

Find position of x in y starting at beginning of y.

x in {string}, y in {string}, return integer

LOCATE(x, y, z)

Find position of x in y starting at z.

x in {string}, y in {string}, z in {integer}, return integer

LPAD(x, y)

Pad input string x with spaces on the left to the length of y.

x in {string}, y in {integer}, return string

LPAD(x, y, z)

Pad input string x on the left to the length of y using character z.

x in {string}, y in {string}, z in {character}, return string

LTRIM(x)

Left trim x of blank chars.

x in {string}, return string

QUERYSTRING(path [, expr [AS name] …])

Returns a properly encoded query string appended to the given path. Null valued expressions are omitted, nd a null path is treated as ". Names are optional for column reference expressions. For example, QUERYSTRING('path', 'value' as "&x", ' & ' as y, null as z) returns 'path?%26x=value&y=%20%26%20'

path, expr in {string}. name is an identifier.

REPEAT(str1,instances)

Repeat string1 a specified number of times

str1 in {string}, instances in {integer} return string.

RIGHT(x, y)

Get right y characters of x

x in {string}, y in {integer}, return string

RPAD(input string x, pad length y)

Pad input string x with spaces on the right to the length of y

x in {string}, y in {integer}, return string

RPAD(x, y, z)

Pad input string x on the right to the length of y using character z

x in {string}, y in {string}, z in {character}, return string

RTRIM(x)

Right trim x of blank chars

x is string, return string

SPACE(x)

Repeat the space character x number of times

x is integer, return string

SUBSTRING(x, y) SUBSTRING(x FROM y)

[b] Get substring from x, from position y to the end of x

y in {integer}

SUBSTRING(x, y, z) SUBSTRING(x FROM y FOR z)

[b] Get substring from x from position y with length z

y, z in {integer}

TRANSLATE(x, y, z)

Translate string x by replacing each character in y with the character in z at the same position.

x in {string}

TRIM([[LEADING|TRAILING|BOTH] [x] FROM] y)

Trim the leading, trailing, or both ends of a string y of character x. If LEADING/TRAILING/BOTH is not specified, BOTH is used. If no trim character x is specified, then the blank space ’ is used.

x in {character}, y in {string}

UCASE(x)

Uppercase of x

x in {string}

UNESCAPE(x)

Unescaped version of x. Possible escape sequences are \b - backspace, \t - tab, \n - line feed, \f - form feed, \r - carriage return. \uXXXX, where X is a hex value, can be used to specify any unicode character. \XXX, where X is an octal digit, can be used to specify an octal byte value. If any other character appears after an escape character, that character will appear in the output and the escape character will be ignored.

x in {string}

[a] Non-ASCII range characters or integers used in these functions may produce different results or exceptions depending on where the function is evaluated (Teiid Spring Boot vs. source). Teiid Spring Boot’s uses Java default int to char and char to int conversions, which operates over UTF16 values.

[b] The substring function depending upon the source does not have consistent behavior with respect to negative from/length arguments nor out of bounds from/length arguments. The default Teiid Spring Boot behavior is:

  • Return a null value when the from value is out of bounds or the length is less than 0

  • A zero from index is effective the same as 1.

  • A negative from index is first counted from the end of the string.

Some sources, however, can return an empty string instead of null, and some sources are not compatible with negative indexing.

TO_CHARS

Return a CLOB from the binary large object (BLOB) with the given encoding.

TO_CHARS(x, encoding [, wellformed])

BASE64, HEX, UTF-8-BOM and the built-in Java Charset names are valid values for the encoding [b]. x is a BLOB, encoding is a string, wellformed is a boolean, and returns a CLOB. The two argument form defaults to wellformed=true. If wellformed is false, the conversion function will immediately validate the result such that an unmappable character or malformed input will raise an exception.

TO_BYTES

Return a BLOB from the CLOB with the given encoding.

TO_BYTES(x, encoding [, wellformed])

BASE64, HEX, UTF-8-BOM and the builtin Java Charset names are valid values for the encoding [b]. x in a CLOB, encoding is a string, wellformed is a boolean and returns a BLOB. The two argument form defaults to wellformed=true. If wellformed is false, the conversion function will immediately validate the result such that an unmappable character or malformed input will raise an exception. If wellformed is true, then unmappable characters will be replaced by the default replacement character for the character set. Binary formats, such as BASE64 and HEX, will be checked for correctness regardless of the wellformed parameter.

[b] For more information about Charset names, see the Charset docs.

REPLACE

Replace all occurrences of a given string with another.

REPLACE(x, y, z)

Replace all occurrences of y with z in x. x, y, z are strings and the return value is a string.

REGEXP_REPLACE

Replace one or all occurrences of a given pattern with another string.

REGEXP_REPLACE(str, pattern, sub [, flags])

Replace one or more occurrences of pattern with sub in str. All arguments are strings and the return value is a string.

The pattern parameter is expected to be a valid Java regular expression

The flags argument can be any concatenation of any of the valid flags with the following meanings:

Flag Name Meaning

g

Global

Replace all occurrences, not just the first.

m

Multi-line

Match over multiple lines.

i

Case insensitive

Match without case sensitivity.
Usage:

The following will return "xxbye Wxx" using the global and case insensitive options.

Example regexp_replace
regexp_replace('Goodbye World', '[g-o].', 'x', 'gi')

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