更新日期:2024年09月11日
本示例实现了使用可更新结果集获取AUTO_INCREMENT 列的值。
示例如下:
package com.gbase.jdbc.simple;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
GBase 8a 程序员手册JDBC 篇
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import java.sql.SQLException;
import java.sql.Statement;
public class SampleUpdatableResultSet {
private
static
final
String
URL
=
"jdbc:gbase://192.168.111.95:5258/test?user=sysdba&password=";
public static void main(String[] args) {
try {
(new SampleUpdatableResultSet()).test();
} catch (Exception ex) {
}
}
public void test() throws Exception {
Connection conn = null;
try {
Class.forName("com.gbase.jdbc.Driver").newInstance();
conn = DriverManager
.getConnection(URL);
Statement stmt = null;
ResultSet rs = null;
try {
stmt = conn.createStatement(
java.sql.ResultSet.TYPE_FORWARD_ONLY,
java.sql.ResultSet.CONCUR_UPDATABLE);
// 创建表
stmt.executeUpdate("DROP
TABLE
IF
EXISTS
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autoIncTutorial");
stmt.executeUpdate("CREATE TABLE autoIncTutorial ("
+ "priKey INT NOT NULL AUTO_INCREMENT, "
+
"dataField
VARCHAR(64),
PRIMARY
KEY
(priKey))");
// 获取自增一字段值
rs = stmt.executeQuery("SELECT priKey, dataField "
+ "FROM autoIncTutorial");
rs.moveToInsertRow();
rs.updateString("dataField", "AUTO INCREMENT here?");
rs.insertRow();
rs.last();
int autoIncKeyFromRS = rs.getInt("priKey");
rs.close();
rs = null;
System.out.println("Key returned for inserted row: "
+ autoIncKeyFromRS);
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException ex) {
}
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException ex) {
GBase 8a 程序员手册JDBC 篇
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}
}
}
} catch (SQLException ex) {
// 处理错误
System.out.println("SQLException: " + ex.getMessage());
System.out.println("SQLState: " + ex.getSQLState());
System.out.println("VendorError: " + ex.getErrorCode());
} finally {
conn.close();
}
}
}
+-------------------+
1 row in set
示例3:D 为“0”,返回值不包含小数点和小数部分。
GBase 8a MPP Cluster 产品手册
5 数据库管理指南
文档版本953(2022-09-15)
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770
gbase> SELECT TRUNCATE(1.999,0) FROM dual;
+-------------------+
| TRUNCATE(1.999,0) |
+-------------------+
|
1 |
+-------------------+
1 row in set
示例4:X 为“-1.999”,小数点后保留一位。
gbase> SELECT TRUNCATE(-1.999,1) FROM dual;
+--------------------+
| TRUNCATE(-1.999,1) |
+--------------------+
|
-1.9 |
+--------------------+
1 row in set
示例5:D 为-2,个位十位归零。
gbase> SELECT TRUNCATE(122,-2) FROM dual;
+------------------+
| TRUNCATE(122,-2) |
+------------------+
|
100 |
+------------------+
1 row in set
示例6:X 为表达式。
gbase> SELECT TRUNCATE(10.28*100,0) FROM dual;
+-----------------------+
| TRUNCATE(10.28*100,0) |
+-----------------------+
|
1028 |
+-----------------------+
1 row in set