Trail: JDBC(TM) Database Access(3)
程序员文章站
2022-05-11 23:45:32
...
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_SENSIT
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
?
?