Substring ( string text FROM pattern text FOR escape text ) → textĮxtracts the first substring matching SQL regular expression see Section 9.7.2. Substring ( string text FROM pattern text ) → textĮxtracts the first substring matching POSIX regular expression see Section 9.7.3. Substring ( string text ) → textĮxtracts the substring of string starting at the start'th character if that is specified, and stopping after count characters if that is specified. Returns first starting index of the specified substring within string, or zero if it's not present. Position ( substring text IN string text ) → integer Overlay('Txxxxas' placing 'hom' from 2 for 4) → Thomas If count is omitted, it defaults to the length of newsubstring. Replaces the substring of string that starts at the start'th character and extends for count characters with newsubstring. Overlay ( string text PLACING newsubstring text FROM start integer ) → text Since this version of the function accepts type character directly, it will not strip trailing spaces. Octet_length('josé') → 5 (if server encoding is UTF8) This function can only be used when the server encoding is UTF8. The optional form key word specifies the form: NFC (the default), NFD, NFKC, or NFKD. Returns number of characters in the string.Ĭonverts the string to all lower case, according to the rules of the database's locale.Ĭonverts the string to the specified Unicode normalization form. Returns number of bits in the string (8 times the octet_length). Note that checking for normalization using this expression is often faster than normalizing possibly already normalized strings. This expression can only be used when the server encoding is UTF8. Text IS NORMALIZED → booleanĬhecks whether the string is in the specified Unicode normalization form. If you want to concatenate an array's text equivalent, cast it to text explicitly.) (The non-string input cannot be of an array type, because that would create ambiguity with the array || operators. Then use it in whatever part of your query that makes sense.Converts the non-string input to text, then concatenates the two strings. This will output: REGEXP_REPLACE(REGEXP_REPLACE('input test string, 'test', '', 'gi'), 'foo', '', 'gi') So that finally, when no more substrings are in the list to remove, the final aggregated query is returned. Then, recursively calls the function again with elements and append each REGEXP query to the passed parameter. The code splits the comma separated string to a list of substrings to remove, Creates a REGEXP_REPLACE function in sql with the first substring. Replace_psql_string("test,foo", "input test string") Return self.replace_psql_string(','.join(ss), query) This is a generic recursive function written in python (but can easily be replicated in whatever language you prefer) That takes in the original string and a list of substrings to be removed: def replace_psql_string(str_to_remove, query): Replace characters with multi-character strings The result of the update is following: Juhanao ![]() Updates table so all predefined letters are translated and the change is saved to the database. update xyz set name = translate(name, 'ä,ü,Ü', 'a,u,U') ![]() Translates all letters ä to a, ü to u and Ü to U. ![]() The result of the update is following: JuhaenaeoĮxample of translate function: select translate(name, 'ä,ü,Ü', 'a,u,U') from xyz update xyz set name = replace(replace(replace(name, 'ä', 'ae'), 'ü', 'ue'), 'Ü', 'Ue') Ĭhanges letters and updates rows. Not very nice, but in the example all ä become ae, ü become ue, and Ü become 'Ue'. select replace(name, 'ä', 'ae') from xyz This function replaces letter ä in the name column with letter a. Some data to play with: drop table if exists xyz Įxample of replace function: select replace(name, 'ä', 'a') from xyz If you want to translate some letters to other letters you can user function translate(string text, from text, to text) that replaces any character in a string that matches a character in the from by the corresponding character in the to set. The replace function can be used to replace one character to several characters. If you want just to replace one or few characters you can use function replace(string text, from text, to text) that replaces all occurrences in string substring.
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