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## Functions on Strings

This section describes various functions on strings.

To follow along with the examples in the section, create `users` table that provides information about users. See the seq_distinct function in Functions on Sequences section for `users` table creation.

The following string functions are supported:

Table 12-7 String Functions

Function | Description
--- | ---
substring Function | Extracts a substring from a string based on a specified starting position and length.
concat Function | Returns a single value of concatenating the two arguments.
upper Function | Converts the characters in the string to uppercase.
lower Function | Converts the characters in the string to lowercase.
trim Function | Returns a string with leading, trailing, or both sets of characters trimmed.
ltrim Function | Returns a string with leading characters trimmed.
rtrim Function | Returns a string with trailing characters trimmed.
length Function | Returns the length of the character string.
contains Function | Returns a boolean indicating if the search string is present in the source string.
starts_with Function | Returns a boolean indicating if the source string begins with the search string.
ends_with Function | Returns a boolean indicating if the source string ends with the search string.
index_of Function | Returns the position of the first character of the search string at its first occurrence.
replace Function | Returns the source string with each occurrence of the search string replaced by the replacement string.
reverse Function | Returns the characters of the source string in the reverse order.