在SQL中从String提取值

Question

I have a SQL table with a column containing XML. It's not pretty but it is part of the project and noch changeable.

Now I need to extract a value from a specific element of this XML. Value is a federal state, so the length of the value is variable, what means that

SUBSTRING ( expression ,start , length )

is not an option, as i can't say how long my value will be.

Is there a function that allows to search between two expression, like

FOO ('state>', '</state') 

or anything in that direction?

EDIT:

I'm using MySQL 5.6

Example:

<root>
  <person>
    <name>Michael</name>
    <state>Berlin</state>
  </person>
</root>

my output should be

Berlin

where a different person can have a different state and so length of value is not allways the same.

thanks for your time.

Answer 1

INSTR (str, pattern)

was the solution

and my script to select the value in my string looks like this

SELECT ID, substring(
xml,
instr(xml, "<state>") + 23,
(instr(xml, "</state>") - (instr(xml, "<state>") + 23))
) AS STATE
FROM tablexml 
WHERE xml
LIKE '%value%';

Answer 2

You can use substring_index() :

select substring_index(substring_index(expression, '<state'>, 2), '</state>', -1) as state
from t;