What does it mean when Statement.executeUpdate() returns -1?

Question

A query that works in management studio and in the executeUpdatemakes that same executeUpdate return -1, which is undefined in any doc

Answer 1

So 4 years later, Microsoft has open sourced their JDBC driver on Github. I got a notification about this question today, and went and had a look, and I believe I have found the culprit here, mssql-jdbc/src/main/java/com/microsoft/sqlserver/jdbc/SQLServerStatement.java:1713.

Basically, the driver tries to understand what SQL Server sends back if it is not a definite result set. According to the comments, it goes like this:

1. Check for errors first. (ln 1669)

2. Not an error. Is it a result set? (ln 1680)

3. Not an error or a result set. Maybe a result from a T-SQL statement? That is, one of the following:

   • a positive count of the number of rows affected (from INSERT, UPDATE, or DELETE),
   • a zero indicating no rows affected, or the statement was DDL, or
   • a -1 indicating the statement succeeded, but there is no update count information available (translates to Statement.SUCCESS_NO_INFO in batch update count arrays). (ln 1706)

4. None of the above. Last chance here... Going into the parser above, we know moreResults was initially true. If we come out with moreResults false, the we hit a DONE token (either DONE (FINAL) or DONE (RPC in batch)) that indicates that the batch succeeded overall, but that there is no information on individual statements' update counts. This is similar to the last case above, except that there is no update count. That is: we have a successful result (return true), but we have no other information about it (updateCount = -1). (ln 1693)

5. Only way to get here (moreResults is still true, but no apparent results of any kind) is if the TDSParser didn't actually parse anything. That is, we are at EOF in the response. In that case, there truly are no more results. We're done. (ln 1717)

(Emphasis mine)

So you guys were right in the end. SQL simply can't tell how many rows are affected, and defaults to -1. :)