Interface PreparedStatement的execute(), executeQuery(), executeUpdate()方法

execute
boolean execute()
                throws SQLException
Executes the SQL statement in this PreparedStatement object, which may be any kind of SQL statement. Some prepared statements return multiple results; the execute method handles these complex statements as well as the simpler form of statements handled by the methods executeQuery and executeUpdate.
The execute method returns a boolean to indicate the form of the first result. You must call either the method getResultSet or getUpdateCount to retrieve the result; you must call getMoreResults to move to any subsequent result(s).


Returns:
true if the first result is a ResultSet object; false if the first result is an update count or there is no result
Throws:
SQLException - if a database access error occurs; this method is called on a closed PreparedStatement or an argument is supplied to this method
See Also:
Statement.execute(java.lang.String), Statement.getResultSet(), Statement.getUpdateCount(), Statement.getMoreResults()

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executeQuery
ResultSet executeQuery()
                       throws SQLException
Executes the SQL query in this PreparedStatement object and returns the ResultSet object generated by the query.

Returns:
a ResultSet object that contains the data produced by the query; never null
Throws:
SQLException - if a database access error occurs; this method is called on a closed PreparedStatement or the SQL statement does not return a ResultSet object

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executeUpdate
int executeUpdate()
                  throws SQLException
Executes the SQL statement in this PreparedStatement object, which must be an SQL Data Manipulation Language (DML) statement, such as INSERT, UPDATE or DELETE; or an SQL statement that returns nothing, such as a DDL statement.

Returns:
either (1) the row count for SQL Data Manipulation Language (DML) statements or (2) 0 for SQL statements that return nothing
Throws:
SQLException - if a database access error occurs; this method is called on a closed PreparedStatement or the SQL statement returns a ResultSet object