From: cdcr440 at hotmail dot com Operating system: WinNT PHP version: 4.3.1 PHP Bug Type: MSSQL related Bug description: MSSQL: "Changed database context to" error when running query
Description: ------------ When selecting a database with mssql_select_db(), the error "Changed database context to 'XXX'". DB server is MSSQL 2000. The problem seems to be the result of running a query and the next time the script tries to select the database, it fails with the above message, which I wouldn't expect from mssql_query(). The failing query will first run for a long time and fail with the above message. All subsequent attempts to select the database will fail with the same message. But running other queries in other scripts will be successful. The behaviour of the bug is hard to predict and I haven't been able to design a query that will surely generate the problem. Also the queries that fail with PHP work fine in SQL Analyzer/Enterprise manager (connected as the same user), so it's not a query/SQL problem. The user I use to connect to the database has the target database as default database therefore I wouldn't expect a change of context to be a problem. Also the user can run exactly the same query with a very slightly different value in one of the parameters and succeed(e.g. "hup" in the query for VARCHAR will fail but "hu" for the same column will succeed), so it's not an access right problem. However, the workaround I've found is to use the sa user to connect to the server, which would tend to show that it's a user problem. I thought for a while that it was a problem with number of open connections to the database, but I reduced them and the behaviour of the bug isn't consistent with that as it can occur when very few concurrent connections are open. The bug also has been present in the last few versions of PHP, not only in 4.3.1. I whish I could provide more useful information like a core dump, but the failing code is very simple, I haven't figured out what the problem is, and PHP doesn't crash. Disclaimer: I searched for this bug in the bugs database, and found a similar Sybase bug with the reporter didn't provide feedback. I didn't find anything else. My sincere apologies if it has been reported before and I missed it. Reproduce code: --------------- $this->dbID = MSSQL_CONNECT($this->theServer, $this->theUser, $this->thePassword); // theServer etc are object variables mssql_select_db($this->theDB, $this->dbID); Running the query afterward is simply: $this->theResults = mssql_query($this->theQuery, $this->dbID); // where $this->theQuery is the query string The PHP log will simply contain: [07-Jul-2003 17:40:43] PHP Warning: mssql_select_db() [<a href='http://www.php.net/function.mssql-select-db'>function.mssql-select-db</a>]: Unable to select database: XXX in myDB.class on line 57 [07-Jul-2003 17:40:43] PHP Warning: mssql_query() [<a href='http://www.php.net/function.mssql-query'>function.mssql-query</a>]: Query failed in myDB.class on line 261 My php.ini options for MSSQL are as follows: [MSSQL] ; Allow or prevent persistent links. mssql.allow_persistent = On ; Maximum number of persistent links. -1 means no limit. mssql.max_persistent = -1 ; Maximum number of links (persistent+non persistent). -1 means no limit. mssql.max_links = -1 ; Minimum error severity to display. mssql.min_error_severity = 10 ; Minimum message severity to display. mssql.min_message_severity = 10 ; Compatability mode with old versions of PHP 3.0. mssql.compatability_mode = Off ; Valid range 0 - 2147483647. Default = 4096. mssql.textlimit = 10000000 ; Valid range 0 - 2147483647. Default = 4096. mssql.textsize = 10000000 ; Limits the number of records in each batch. 0 = all records in one batch. ;mssql.batchsize = 15 -- Edit bug report at http://bugs.php.net/?id=24522&edit=1 -- Try a CVS snapshot (php4): http://bugs.php.net/fix.php?id=24522&r=trysnapshot4 Try a CVS snapshot (php5): http://bugs.php.net/fix.php?id=24522&r=trysnapshot5 Fixed in CVS: http://bugs.php.net/fix.php?id=24522&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=24522&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=24522&r=needtrace Try newer version: http://bugs.php.net/fix.php?id=24522&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=24522&r=support Expected behavior: http://bugs.php.net/fix.php?id=24522&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=24522&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=24522&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=24522&r=globals PHP 3 support discontinued: http://bugs.php.net/fix.php?id=24522&r=php3 Daylight Savings: http://bugs.php.net/fix.php?id=24522&r=dst IIS Stability: http://bugs.php.net/fix.php?id=24522&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=24522&r=gnused
