JDBC学习笔记(5)：数据库的基本操作CRUD

1.查询

public static void read() throws SQLException {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;

try {
conn = JdbcUtils.getConnection();
stmt = conn.createStatement();
rs = stmt.executeQuery("select * from user");

while(rs.next()) {
System.out.println(rs.getInt("id") + "\t"
+ rs.getString("name") + "\t"
+ rs.getDate("birthday") + "\t"
+ rs.getFloat("money"));
}
} finally {
JdbcUtils.close(rs, stmt, conn);
}
}

【运行结果】：

1 zhangs 1985-01-01 100.0
2 lisi 1986-01-01 200.0
3 wangwu 1987-01-01 300.0

2.增减一条记录，由于id是自增的，所以不需要重复插入数据：

public static void create() throws SQLException {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;

try {
conn = JdbcUtils.getConnection();
stmt = conn.createStatement();
String sql = "insert into user(name,birthday,money) values('zhaoliu','1990-01-01',400)";
int i = stmt.executeUpdate(sql);
System.out.println("i="+i);
} finally {
JdbcUtils.close(rs, stmt, conn);
}
}

【运行结果】：

i=1 //表示成功插入一条记录
【查询数据库结果】：多了一条记录



3.将id=1的money修改为400

public static void update() throws SQLException {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;

try {
conn = JdbcUtils.getConnection();
stmt = conn.createStatement();

String sql = "update user set money=400 where id=1";
int i = stmt.executeUpdate(sql);
System.out.println("i = " + i);
} finally {
JdbcUtils.close(rs, stmt, conn);
}

}

【运行结果】：

i = 1
【查询数据库结果】：



4.删除id=4的记录

public static void delete() throws SQLException {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;

try {
conn = JdbcUtils.getConnection();
stmt = conn.createStatement();
String sql = "delete from user where id=4";
int i = stmt.executeUpdate(sql);
System.out.println("i=====" + i);
} finally{
JdbcUtils.close(rs, stmt, conn);
}
}

【运行结果】：

i=====1
【查询数据库结果】：