DatabaseLink`
DatabaseLink`

SQLResultSetOpen

SQLResultSetOpen[query]

makes a result set from an SQL query.

更多信息和选项

  • To use SQLResultSetOpen, you first need to load DatabaseLink using Needs["DatabaseLink`"].
  • The following options can be given:
  • "Mode""ScrollInsensitive"the timeout for the query
    "FetchDirection"Automaticprocessing direction hint to JDBC driver
    "FetchSize"AutomaticJDBC driver hint for filling result sets

范例

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基本范例  (2)

If you find that the examples in this section do not work as shown, you may need to install or restore the example database with the DatabaseLink`DatabaseExamples` package, as described in Using the Example Databases.

Open a connection:

Use SQLSelect instead of SQLExecute:

Options  (3)

"Mode"  (2)

Specify one of "ForwardOnly", "ScrollInsensitive", or "ScrollSensitive", depending on whether the desired result set is scrollable and sensitive to changes in the underlying data:

The mode "MySQLStreaming" is supported by some MySQL drivers. This unscrollable mode is suitable for streaming large result sets with low memory use:

Compute memory in use, including both kernel and Java layers:

Read a conventional forward-only result set 100 rows at a time:

Memory use is relatively high, as the driver is keeping a copy of the result set in memory:

Reset:

Read the result set in streaming mode:

Memory use in the streaming case is relatively low:

"FetchDirection"  (1)

Specify "Forward", "Reverse", or "Unknown" to direct the JDBC driver to employ different fetching and caching strategies: