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JDBC 3种获得mysql插入数据的自增字段值的方法

2015-01-22 11:20 706 查看

1. Retrieving AUTO_INCREMENT Column Values using Statement.getGeneratedKeys()

2. Retrieving AUTO_INCREMENT Column Values using SELECT LAST_INSERT_ID()
Statement stmt = null;

ResultSet rs = null;

Connection conn = null;

try {

Class.forName("com.mysql.jdbc.Driver");

conn = DriverManager

.getConnection("jdbc:mysql://localhost:3306/test","root", "admin");

stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,

java.sql.ResultSet.CONCUR_UPDATABLE);

stmt.executeUpdate("INSERT INTO autoIncTutorial (dataField) " +
"values ('')", Statement.RETURN_GENERATED_KEYS);

int autoIncKeyFromApi = -1;

rs = stmt.getGeneratedKeys();

if (rs.next()) {

autoIncKeyFromApi = rs.getInt(1);

} else {

// throw an exception from here

}

stmt.executeUpdate("INSERT INTO autoIncTutorial (dataField) " + "values ('')");

int autoIncKeyFromFunc = -1;

rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

if (rs.next()) {

autoIncKeyFromFunc = rs.getInt(1);

} else {

// throw an exception from here

}

http://blog.sina.com.cn/s/blog_4cc16fc50100c6sz.html

mysql 官方说明：

http://dev.mysql.com/doc/connector-j/en/connector-j-usagenotes-last-insert-id.html

6.4 Retrieving

AUTO_INCREMENT

Column Values through JDBC

Before version 3.0 of the JDBC API, there was no standard way of retrieving key values from databases that supported auto increment or identity columns. With older JDBC drivers for MySQL, you could always use a MySQL-specific method on the

Statement

interface, or issue the query

SELECT LAST_INSERT_ID()

after issuing an

INSERT

to a table that had an

AUTO_INCREMENT

key. Using the MySQL-specific method call isn't portable, and issuing a

SELECT

to get the

AUTO_INCREMENT

key's value requires another round-trip to the database, which isn't as efficient as possible. The following code snippets demonstrate the three different ways to
retrieve

AUTO_INCREMENT

values. First, we demonstrate the use of the new JDBC 3.0 method

getGeneratedKeys()

which is now the preferred method to use if you need to retrieve

AUTO_INCREMENT

keys and have access to JDBC 3.0. The second example shows how you can retrieve the same value using a standard

SELECT LAST_INSERT_ID()

query. The final example shows how updatable result sets can retrieve the

AUTO_INCREMENT

value when using the

insertRow()

method.

Example 6.8 Connector/J: Retrieving
AUTO_INCREMENT
column values using
Statement.getGeneratedKeys()

Statement stmt = null;
ResultSet rs = null;

try {

//
// Create a Statement instance that we can use for
// 'normal' result sets assuming you have a
// Connection 'conn' to a MySQL database already
// available

stmt = conn.createStatement();

//
// Issue the DDL queries for the table for this example
//

stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
stmt.executeUpdate(
"CREATE TABLE autoIncTutorial ("
+ "priKey INT NOT NULL AUTO_INCREMENT, "
+ "dataField VARCHAR(64), PRIMARY KEY (priKey))");

//
// Insert one row that will generate an AUTO INCREMENT
// key in the 'priKey' field
//

stmt.executeUpdate(
"INSERT INTO autoIncTutorial (dataField) "
+ "values ('Can I Get the Auto Increment Field?')",
Statement.RETURN_GENERATED_KEYS);

//
// Example of using Statement.getGeneratedKeys()
// to retrieve the value of an auto-increment
// value
//

int autoIncKeyFromApi = -1;

rs = stmt.getGeneratedKeys();

if (rs.next()) {
autoIncKeyFromApi = rs.getInt(1);
} else {

// throw an exception from here
}

System.out.println("Key returned from getGeneratedKeys():"
+ autoIncKeyFromApi);
} finally {

if (rs != null) {
try {
rs.close();
} catch (SQLException ex) {
// ignore
}
}

if (stmt != null) {
try {
stmt.close();
} catch (SQLException ex) {
// ignore
}
}
}

Example 6.9 Connector/J: Retrieving
AUTO_INCREMENT
column values using
SELECT LAST_INSERT_ID()

Statement stmt = null;
ResultSet rs = null;

try {

//
// Create a Statement instance that we can use for
// 'normal' result sets.

stmt = conn.createStatement();

//
// Issue the DDL queries for the table for this example
//

stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
stmt.executeUpdate(
"CREATE TABLE autoIncTutorial ("
+ "priKey INT NOT NULL AUTO_INCREMENT, "
+ "dataField VARCHAR(64), PRIMARY KEY (priKey))");

//
// Insert one row that will generate an AUTO INCREMENT
// key in the 'priKey' field
//

stmt.executeUpdate(
"INSERT INTO autoIncTutorial (dataField) "
+ "values ('Can I Get the Auto Increment Field?')");

//
// Use the MySQL LAST_INSERT_ID()
// function to do the same thing as getGeneratedKeys()
//

int autoIncKeyFromFunc = -1;
rs = stmt.executeQuery("SELECT LAST_INSERT_ID()");

if (rs.next()) {
autoIncKeyFromFunc = rs.getInt(1);
} else {
// throw an exception from here
}

System.out.println("Key returned from " +
"'SELECT LAST_INSERT_ID()': " +
autoIncKeyFromFunc);

} finally {

if (rs != null) {
try {
rs.close();
} catch (SQLException ex) {
// ignore
}
}

if (stmt != null) {
try {
stmt.close();
} catch (SQLException ex) {
// ignore
}
}
}

Example 6.10 Connector/J: Retrieving
AUTO_INCREMENT
column values in
Updatable ResultSets

Statement stmt = null;
ResultSet rs = null;

try {

//
// Create a Statement instance that we can use for
// 'normal' result sets as well as an 'updatable'
// one, assuming you have a Connection 'conn' to
// a MySQL database already available
//

stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
java.sql.ResultSet.CONCUR_UPDATABLE);

//
// Issue the DDL queries for the table for this example
//

stmt.executeUpdate("DROP TABLE IF EXISTS autoIncTutorial");
stmt.executeUpdate(
"CREATE TABLE autoIncTutorial ("
+ "priKey INT NOT NULL AUTO_INCREMENT, "
+ "dataField VARCHAR(64), PRIMARY KEY (priKey))");

//
// Example of retrieving an AUTO INCREMENT key
// from an updatable result set
//

rs = stmt.executeQuery("SELECT priKey, dataField "
+ "FROM autoIncTutorial");

rs.moveToInsertRow();

rs.updateString("dataField", "AUTO INCREMENT here?");
rs.insertRow();

//
// the driver adds rows at the end
//

rs.last();

//
// We should now be on the row we just inserted
//

int autoIncKeyFromRS = rs.getInt("priKey");

System.out.println("Key returned for inserted row: "
+ autoIncKeyFromRS);

} finally {

if (rs != null) {
try {
rs.close();
} catch (SQLException ex) {
// ignore
}
}

if (stmt != null) {
try {
stmt.close();
} catch (SQLException ex) {
// ignore
}
}
}

Running the preceding example code should produce the following output:

Key returned from getGeneratedKeys(): 1
Key returned from SELECT LAST_INSERT_ID(): 1
Key returned for inserted row: 1

At times, it can be tricky to use the

SELECT LAST_INSERT_ID()

query, as that function's value is scoped to a connection. So, if some other query happens on the same connection, the value is overwritten. On the other hand, the

getGeneratedKeys()

method is scoped by the

Statement

instance, so it can be used even if other queries happen on the same connection, but not on the same

Statement

instance.

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JDBC 3种获得mysql插入数据的自增字段值的方法

6.4 RetrievingAUTO_INCREMENT Column Values through JDBC

6.4 Retrieving
AUTO_INCREMENT
Column Values through JDBC