Statements
Once you have created a Connection
, you can begin using it to
execute SQL statements . This is usually done via Statement
objects. There are actually three
kinds of statements in JDBC :
Statement
Represents a basic SQL statement
PreparedStatement
Represents a precompiled SQL statement, which can offer improved performance
CallableStatement
Allows JDBC programs complete access to stored procedures within the database itself
We’re going to discuss just the Statement
object for now; PreparedStatement
and CallableStatement
are covered in detail
later in this chapter.
To get a Statement
object,
call the createStatement()
method
of a Connection
:
Statement stmt = con.createStatement();
Once you have created a Statement
, use it to execute SQL statements.
A statement can be either a query that returns results or an operation
that manipulates the database in some way. If you are performing a
query, use the executeQuery()
method of the Statement
object:
ResultSet rs = stmt.executeQuery("SELECT * FROM CUSTOMERS");
Here we’ve used executeQuery()
to run a SELECT
statement. This call returns a
ResultSet
object that contains the
results of the query (we’ll take a closer look at ResultSet
in the next section).
Statement
also provides an
executeUpdate()
method for running
SQL statements that don’t return results, such as the UPDATE
and DELETE
statements. executeUpdate()
returns an integer that
indicates the number of rows in the database that were altered.
If you don’t know whether a SQL statement ...
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