Anomalous commit/rollback behavior

Question

David Goldsmith 2011-8-8

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/13319-anomalous-commit-rollback-behavior

Please observe:

K>> get(conn, 'AutoCommit') % AutoCommit is Off

ans =
off

K>> curs = fetch(exec(conn, ['select * from RawValue r inner join CalculatedValue c '... 'on r.RawValueID=c.RawValueID where r.RealTimeFlagsID=-9998 and '... 'not r.SiteID like ''ADM%'''])) % Matlab just added the queried data to the database; note that (a lot of) data is being returned

    curs =
        Attributes: []
              Data: {5271x58 cell}
    DatabaseObject: [1x1 database]
          RowLimit: 0
          SQLQuery: [1x141 char]
           Message: []
              Type: 'Database Cursor Object'
         ResultSet: [1x1 sun.jdbc.odbc.JdbcOdbcResultSet]
            Cursor: [1x1 com.mathworks.toolbox.database.sqlExec]
         Statement: [1x1 sun.jdbc.odbc.JdbcOdbcStatement]
             Fetch: [1x1 com.mathworks.toolbox.database.fetchTheData]

K>> commit(conn) % Now I (ostensibly) commit it

K>> curs = fetch(exec(conn, ['select * from RawValue r inner join CalculatedValue c '... 'on r.RawValueID=c.RawValueID where r.RealTimeFlagsID=-9998 and '... 'not r.SiteID like ''ADM%'''])) % Yup, it's still there! :)

curs =
          Attributes: []
              Data: {5271x58 cell}
    DatabaseObject: [1x1 database]
          RowLimit: 0
          SQLQuery: [1x141 char]
           Message: []
              Type: 'Database Cursor Object'
         ResultSet: [1x1 sun.jdbc.odbc.JdbcOdbcResultSet]
            Cursor: [1x1 com.mathworks.toolbox.database.sqlExec]
         Statement: [1x1 sun.jdbc.odbc.JdbcOdbcStatement]
             Fetch: [1x1 com.mathworks.toolbox.database.fetchTheData]

K>> rollback(conn) % My understanding is that this should now have no effect

K>> curs = fetch(exec(conn, ['select * from RawValue r inner join CalculatedValue c '... 'on r.RawValueID=c.RawValueID where r.RealTimeFlagsID=-9998 and '... 'not r.SiteID like ''ADM%'''])) *% But wait, there's less! :(*

curs =
          Attributes: []
              Data: {'No Data'}
    DatabaseObject: [1x1 database]
          RowLimit: 0
          SQLQuery: [1x141 char]
           Message: []
              Type: 'Database Cursor Object'
         ResultSet: [1x1 sun.jdbc.odbc.JdbcOdbcResultSet]
            Cursor: [1x1 com.mathworks.toolbox.database.sqlExec]
         Statement: [1x1 sun.jdbc.odbc.JdbcOdbcStatement]
             Fetch: [1x1 com.mathworks.toolbox.database.fetchTheData]

Can someone please explain this result to me?

Thanks!

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Oleg Komarov 2011-8-8

In the example you're using plain SELECT queries wich do not affect the content of a TABLE.

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Anomalous commit/rollback behavior

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