Update statement with joining other tables

Question

Hi ,
I have two table one is containing xml file , basically i need to read from those xml file then update to another table based on some condition.
UPDATE TRCB_XBRL_STG_2 STG
SET PROFIT =
  case when xbrl.isconsolidatedacc='Y' and EXTRACTVALUE(XBRL.XBRLFILE,'//PROFIT ', 'xmlns:acra="..."') is not null
  THEN EXTRACTVALUE(XBRL.XBRLFILE,'//PROFIT ', 'xmlns:acra="..."')
  WHEN XBRL.ISCONSOLIDATEDACC='N' AND EXTRACTVALUE(XBRL.XBRLFILE,'//PROFIT ', 'xmlns:acra="..') IS NOT NULL
  THEN extractValue(XBRL.xbrlfile,'//PROFIT ', 'xmlns:acra=".."')
  ELSE STG.PROFIT
  END,
  SET REVENUE=
  case when xbrl.isconsolidatedacc='Y' and EXTRACTVALUE(XBRL.XBRLFILE,'//REVENUE', 'xmlns:acra="..."') is not null
  THEN EXTRACTVALUE(XBRL.XBRLFILE,'//REVENUE.', 'xmlns:acra="..."')
  WHEN XBRL.ISCONSOLIDATEDACC='N' AND EXTRACTVALUE(XBRL.XBRLFILE,'//REVENUE', 'xmlns:acra="..') IS NOT NULL
  THEN extractValue(XBRL.xbrlfile,'//REVENUE', 'xmlns:acra="REVENUE"')
  ELSE STG.REVENUE
  END,
  ... (around 100 columns)
FROM  TRCB_XBRL xbrl ,TRCB_XBRL_STG_2 STG
WHERE STG.XBRL_ID = XBRL.XBRL_ID Number of columns are around 100 , please anyone suggest how to use update statement with joining two tables.

Answer 1

Hi,
If all the values needed to update a given row of table_x are coming from the same row of table_y (or from the same row of a result set of a query involving any number of tables), then you can do something like this:
UPDATE  table_x  x
SET     (col1, col2, col3, ...)
=     (
         SELECT  NVL (y.col1, x.col1)
         ,         NVL (y.col2, x.col2)
         ,         NVL (y.col3, x.col3)
         FROM    table_y  y
         WHERE   x.pkey   = y.expr
         AND         ...
WHERE   ...
;If the WHERE clause depends on the same row of table_y, then it will probably be simpler and more efficient to use MERGE instead of UPDATE.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all the tables involved, and the results you want from that data.
In the case of a DML operation (such as UPDATE) the sample data should show what the tables are like before the DML, and the results will be the contents of the changed table(s) after the DML.
Explain, using specific examples, how you get those results from that data.
Always say what version of Oracle you're using (e.g. 11.2.0.2.0).
See the forum FAQ {message:id=9360002}