Sanity Check: (+) Operator in WHERE Clause for Oracle DB? [duplicate]

This question already has answers here: Closed 11 years ago.

Possible Duplicate:

Oracle “(+)” Operator

So I was given a script with the followin开发者_开发知识库g:

SELECT BLAH
  FROM A_TABLE T1, A_TABLE T2, A_TABLE T3 
 WHERE T2.FIELD_1(+) = T1.FIELD_1
   AND T3.FIELD_1(+) = T2.FIELD_1
   ... etc a few more AND clauses that do that same thing

I need to convert this script to MSSQL Server but I have no clue what this operator is doing. Is it possible that this is some kind of typo?

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That's the old Oracle syntax for outer joins. You should use the ANSI join syntax instead:

SELECT BLAH
  FROM A_TABLE T1
  LEFT JOIN A_TABLE T2 ON T2.FIELD_1 = T1.FIELD_1
  LEFT JOIN A_TABLE T3 ON T3.FIELD_1 = T2.FIELD_1
 WHERE ... etc

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It is the Oracle notation for LEFT JOIN.

It means

SELECT BLAH
  FROM A_TABLE T1
  LEFT JOIN A_TABLE T2 ON T2.FIELD_1 = T1.FIELD_1
  LEFT JOIN A_TABLE T3 ON T3.FIELD_1 = T2.FIELD_1
   ... etc a few more AND clauses that do that same thing

The (+) is put against the optional side. Read also:

• http://www.dba-oracle.com/art_sql_iso_99.htm
• Difference between Oracle's plus (+) notation and ansi JOIN notation?