Trail: JDBC(TM) Database Access(3)
编程技术 / houtizong 发布于 3年前 166
java.sql,javax.sql,javax.naming包
默认TYPE_FORWARD_ONLY:结果集只能向前滚动,只能调用next(),不能重定位游标
TYPE_SCROLL_INSENSITIVE,TYPE_SCROLL_SENSITIVE:可以重定位游标
TYPE_SCROLL_INSENSITIVE:底层修改不会反映到结果集
TYPE_SCROLL_SENSITIVE:会实时显示真实数据
默认CONCUR_READ_ONLY:不能更新到底层,只是读取
CONCUR_UPDATABLE:可以更新,可以写入
stmt = con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,//可滚动,实时显示 ResultSet.CONCUR_UPDATABLE);//可写入 ResultSet uprs = stmt.executeQuery( "SELECT * FROM " + dbName + ".COFFEES"); while (uprs.next()) { float f = uprs.getFloat("PRICE"); uprs.updateFloat( "PRICE", f * percentage);//设置某列 uprs.updateRow();//提交 }
stmt = con.createStatement( ResultSet.TYPE_SCROLL_SENSITIVE ResultSet.CONCUR_UPDATABLE); ResultSet uprs = stmt.executeQuery( "SELECT * FROM " + dbName + ".COFFEES"); uprs.moveToInsertRow();//准备插入 uprs.updateString("COF_NAME", coffeeName); uprs.updateInt("SUP_ID", supplierID); uprs.updateFloat("PRICE", price); uprs.updateInt("SALES", sales); uprs.updateInt("TOTAL", total); uprs.insertRow();//提交 uprs.beforeFirst();//游标不能再指向这里
RowSet对象都是JavaBean组件
如果数据库不支持游标滚动,也不支持实时更新,可以用RowSet替代
RowSet有保持连接的和离线的两种
public void createProcedureGetSupplierOfCoffee() throws SQLException { String createProcedure = null; // ... createProcedure = "create procedure GET_SUPPLIER_OF_COFFEE(" + "IN coffeeName varchar(32), " +//in "OUT supplierName varchar(40)) " +//out "begin " + "select SUPPLIERS.SUP_NAME into " + "supplierName " + "from SUPPLIERS, COFFEES " + "where SUPPLIERS.SUP_ID = " + "COFFEES.SUP_ID " + "and coffeeName = COFFEES.COF_NAME; " + "select supplierName; " + "end"; // ...}
createProcedure = "create procedure RAISE_PRICE(" + "IN coffeeName varchar(32), " + "IN maximumPercentage float, " + "INOUT newPrice numeric(10,2)) " +//inout "begin " + "main: BEGIN " + "declare maximumNewPrice " + "numeric(10,2); " + "declare oldPrice numeric(10,2); " + "select COFFEES.PRICE into oldPrice " +...
cs = this.con.prepareCall("{call GET_SUPPLIER_OF_COFFEE(?, ?)}");cs.setString(1, coffeeNameArg);cs.registerOutParameter(2, Types.VARCHAR);cs.executeQuery();String supplierName = cs.getString(2);
cs = this.con.prepareCall("{call RAISE_PRICE(?,?,?)}");cs.setString(1, coffeeNameArg);cs.setFloat(2, maximumPercentageArg);cs.registerOutParameter(3, Types.NUMERIC);cs.setFloat(3, newPriceArg);cs.execute();Because the parameter newPrice (the third parameter in the procedure
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