java模糊查询
String   sql   =   "select   con   from   table_name   where   con   like   '%?% ' ";   //   ?号是占位符
PreparedStatement   prepare   =   conn.prepareStatement(sql);
prepare.setString(1, "a ");
会报错:   java.sql.SQLException:   [Microsoft][SQLServer   2000   Driver   for   JDBC]Invalid   parameter   binding(s).

当用   String   con   =   "a ";
          sql   =   "select   con   from   table_name   where   con   like   '% "+   con   + "% ' ";
          prepare.executeQuery();
        时,就不会报错了.
为什么在关键字 'like '后面用占位符的时候就会出错呢?

------解决方案--------------------
String sql = "select con from table_name where con like ? "; // ?号是占位符
PreparedStatement prepare = conn.prepareStatement(sql);
prepare.setString(1, "%a% ");


that 's all!
------解决方案--------------------
'%?% '，这样写？号只是字符串%?%中的一个字符，并不是占位符，没有了占位符prepare.setString(1, "a ")时就找不到对应的占位符了。

String sql = "select con from table_name where con like ? "; // ?号是占位符
PreparedStatement prepare = conn.prepareStatement(sql);
prepare.setString(1, "% "+con+ "% ");//con作为参数传进来