Postgres substring example8/16/2023 ![]() Older versions were more permissive.Įither way, with any of these methods the string has to be valid xml or the cast (implicit or explicit) will raise an exception. But there is one exception: if the start position is 1 you can. In PostgreSQL you have to use an user-defined function (see below). This has been tightened with PostgreSQL 9.1 (I think). INSTR with 3 parameters starts searching the specified substring from the specified position of string: Oracle : - Find substring in string starting from 3 position SELECT INSTR abcb, b, 3) FROM dual 4. You'd have to cast to text first: unknown_type_col::text::xml. The example below shows the usage of SUBSTR () function. Obviously, there is no direct conversion implemented between unknown and xml. If I had not cast to a specific type, the type unknown would have been used - which is not the same thing as an untyped string. This works without explicit cast: SELECT xpath('./status/text()'Ī CTE like in my first example needs a type for every column in the "common table expression". An untyped string constant is coerced to xml automatically, but a text column is not. The function xpath() expects the 2nd parameters of type xml. Since you defined your columns to be of type text (instead of xml, you need to cast to xml explicitly. If there can be multiple status items: SELECT id, unnest(xpath('./status/text()', response::xml)) AS status If you are certain there is only a single status tag per row, you can simply extract the first item from the array: SELECT id, (xpath('./status/text()', response::xml)) AS status In response to your question update, this can simply be: SELECT id, xpath('./status/text()', response::xml) AS status Returns an array of xml - with a single element in this case: status SELECT xpath('./status/text()', col) AS status Use the xpath() function: WITH x(col) AS (SELECT 'ERROR_MISSING_DATA'::xml) Response | ERROR_MISSING_DATACOUNTRY_MISSINGUSA1234 Request | ERROR_MISSING_DATACOUNTRY_MISSINGUSA1234 And assume the table name abc_events id | 1870667 Postgresql: Using xpath to extract data from an XML column. get xml or substring value from postgresql table. And the xml that I have shown above is an example of the response. Time | timestamp without time zone | not nullĪnd I want to extract status from each and every request. I want to extract the status from all the rows in my Postgres database. Id | bigint | not null default nextval('events_id_seq'::regclass) So my table structure is like this Column | Type | Modifiers Is there a way to do it? ERROR_MISSING_DATACOUNTRY_MISSINGUSA1234 The status could be of varying sizes like SUCCESS as well so I do not want to use the substring function. I want to extract the status from all the rows in my Postgres database. Below is the column response from my Postgres table. ![]()
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