java - JDBC 结果集类型滚动敏感

Question

ResultSet.TYPE_SCROLL_SENSITIVE怎么样？实际上可以在 JDBC 中工作吗？

Statement stmt = conn.createStatement(
                       ResultSet.TYPE_SCROLL_SENSITIVE,
                       ResultSet.CONCUR_READ_ONLY);`

Answer 1

JDBC specification说:

The type of a ResultSet object determines the level of its functionality in two main areas: (1) the ways in which the cursor can be manipulated and (2) how concurrent changes made to the underlying data source are reflected by the ResultSet object. The latter is called the sensitivity of the ResultSet object.

The three different ResultSet types are described below.

[...]

3. TYPE_SCROLL_SENSITIVE

• The result set is scrollable; its cursor can move both forward and backward relative to the current position, and it can move to an absolute position.
• The result set reflects changes made to the underlying data source while the result set remains open.

The default ResultSet type is TYPE_FORWARD_ONLY.

The method DatabaseMetaData.supportsResultSetType returns true if the specified type is supported by the driver and false otherwise.

If the driver does not support the type supplied to the methods createStatement, prepareStatement, or prepareCall, it generates an SQLWarning on the Connection object that is creating the statement. When the statement is executed, the driver returns a ResultSet object of a type that most closely matches the requested type. An application can find out the type of a ResultSet object by calling the method ResultSet.getType.