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prepareStatement与Statement的区别

1:创建时的区别: 
   Statement stm=con.createStatement(); 
   PreparedStatement pstm=con.prepareStatement(sql); 
执行的时候: 
    stm.execute(sql); 
    pstm.execute(); 
2: pstm一旦绑定了SQL,此pstm就不能执行其他的Sql,即只能执行一条SQL命令。 
stm可以执行多条SQL命令。 
3: 对于执行同构的sql(只有值不同,其他结构都相同),用pstm的执行效率比较的高,对于异构的SQL语句,Statement的执行效率要高。 
4:当需要外部变量的时候,pstm的执行效率更高.

下面是一个statement的列子 : 
Java代码 
package com.JDBC.proc; 

import java.sql.*; 

public class StatementTest { 
      
    public static void main(String args[]){ 
          
        Connection conn=null; 
        Statement stm=null; 
        ResultSet rs=null; 
          
        try { 
            conn=DBTool.getConnection(); 
            String sql="select EmpNo,EName from emp " + 
                    "where empNo=7499"; 
            stm=conn.createStatement(); 
            rs=stm.executeQuery(sql); 
            while(rs.next()){ 
                System.out.println(rs.getInt(1)+"---"+rs.getString(2)); 
            } 
        } catch (SQLException e) { 
            e.printStackTrace(); 
        } catch (Exception e) { 

            e.printStackTrace(); 
        }finally{ 
            DBTool.release(rs, stm, conn); 
            } 
          
    } 
      

}


他的主要作用阐述Statement的用法。

下面是关于prepareStatement的列子: 
Java代码 
package com.JDBC.proc; 

import java.sql.*; 
public class PrepareStatement { 
      
    public static void main(String[] args){ 
          
        Connection conn=null; 
        PreparedStatement psmt=null; 
        ResultSet rs=null; 
          
        try { 
            conn=DBTool.getConnection(); 
            String sql="select EmpNo,Ename " + 
                    "from emp " + 
                    "where EmpNo=?"; 
            psmt=conn.prepareStatement(sql); 
            psmt.setInt(1, 7499); 
              
            rs=psmt.executeQuery(); 
            while(rs.next()){ 
                System.out.println(rs.getInt(1)+"---"+rs.getString(2)); 
                  
            } 
        } catch (SQLException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
        } catch (Exception e) { 
            e.printStackTrace(); 
        }finally{ 
            DBTool.release(rs, psmt, conn); 
        } 
          
    } 

}

prepareStatement与Statement的区别