DB2中SQLJ應用示例

 

// 本例展示怎樣寫用JDBC應用驅動程序存取DB2數據庫的SQLJ應用。 
// 其中bank爲DB2中的數據庫，customer爲bank中的表 
import java.sql.*; 
import sqlj.runtime.*; 
import sqlj.runtime.ref.*; 

#sql iterator App_Cursor1 (String customer_id, String customer_name) ; 
#sql iterator App_Cursor2 (String) ; 

class App 
...{ 

    static 
    ...{ 
        try 
        ...{ 
            // 用 DriverManager 註冊驅動程序 
            Class.forName("COM.ibm.db2.jdbc.app.DB2Driver").newInstance(); 
        } 
        catch (Exception e) 
        ...{ 
            E.PRINTsTACKtRACE(); 
        } 
    } 

    public static void main(String argv[]) 
    ...{ 
        try 
        ...{ 
            aPP_cURSOR1 CURSOR1; 
            aPP_cURSOR2 CURSOR2; 

            sTRING STR1 = NULL; 
            sTRING STR2 = NULL; 
            INT COUNT1; 

            cONNECTION CON = NULL; 

            // url的格式爲：JDBC:DB2:數據庫名 
            sTRING URL = "JDBC:DB2:BANK"; 

            dEFAULTcONTEXT CTX = dEFAULTcONTEXT.GETdEFAULTcONTEXT(); 
            if (ctx == null) 
            ...{ 
                try 
                ...{ 
                    if (argv.length == 0) 
                    ...{ 
                        // 用默認的用戶名和口令連接 
                        con = DriverManager.getConnection(url); 
                    } 
                    else if (argv.length == 2) 
                    ...{ 
                        String userid = argv[0]; 
                        String passwd = argv[1]; 

                        // 用用戶提供的用戶名和口令連接 
                        con = DriverManager.getConnection(url, userid, passwd); 
                    } 
                    else 
                    ...{ 
                        System.out.println(" 用法: java SqljApp [用戶名 口令] "); 
                        System.exit(0); 
                    } 
                    con.setAutoCommit(false); 
                    ctx = new DefaultContext(con); 
                } 
                catch (SQLException e) 
                ...{ 
                    System.out.println("錯誤: 不能得到默認內容"); 
                    System.err.println(e) ; 
                    System.exit(1); 
                } 

                DefaultContext.setDefaultContext(ctx); 
            } 

            // 從數據庫提取數據 
            System.out.println("從數據庫提取一些數據..."); 
            #sql cursor1 = ...{ SELECT customer_id, customer_name from customer }; 

            // 顯示結果集 
            // cursor1.next() 當無更多的行時返回 false 
            System.out.println("得到的結果:"); 
            while (cursor1.next()) 
            ...{ 
                str1 = cursor1.customer_id(); 
                str2 = cursor1.customer_name(); 

                System.out.print (" 客戶編號= " + str1); 
                System.out.print (" 客戶姓名= " + str2); 
                System.out.print (" "); 
            } 
            cursor1.close(); 

            // 從數據庫中獲取客戶數 
            System.out.println(" 獲取客戶表的行數..."); 
            #sql ...{ SELECT count(*) into :count1 from customer }; 
            System.out.println ("客戶表中有 " + count1 + " 行."); 

            // 更新數據 
            str1 = " 1"; 
            System.out.println(" 更新數據... "); 
            #sql 
            ...{ 
                UPDATE customer set customer_name = ´黃亮輝´ where customer_id = :str1 
            }; 

            // 從數據庫中提取更新數據 
            System.out.println(" 從數據庫中提取更新數據..."); 
            #sql cursor2 = ...{ SELECT customer_name from customer where customer_id = :str1 }; 

            // 顯示結果集 
            // cursor2.next() 當無更多行時返回 false 
            System.out.println("得到的結果:"); 
            while (true) 
            ...{ 
                #sql ...{ FETCH :cursor2 INTO :str2 }; 
                if (cursor2.endFetch()) break; 

                System.out.print (" 客戶編號= " + str1); 
                System.out.print (" 客戶姓名= " + str2); 
                System.out.print (" "); 
            } 
            cursor2.close(); 

            // 回滾更新 
            System.out.println(" 回滾更新..."); 
            #sql ...{ ROLLBACK work }; 
            System.out.println("回滾完成."); 
        } 
        catch( Exception e ) 
        ...{ 
            e.printStackTrace(); 
        } 
    } 
}