请假oracle jdbc中使用PreparedStatement setString的问题？

[baoma2000]

我写了两个方法
===========能取出数据===========
conn.prepareStatement("select * from t where a='a' and b='b'");
===========不能取出数据===========
conn.prepareStatement("select * from t where a=? and b=?");
st.setString(1, "a");
st.setString(2, "b");
有人遇到过类似问题吗？

[zdjray]

加上conn.commit()
试试？

[huoyin]

conn.prepareStatement("select * from t where a='?' and b='?'");

[awusoft]

conn.prepareStatement("select * from t where a=? and b=?");
st.setString(1, "a");
st.setString(2, "b");

ResultSet rs = st.executeQuery();这样也不行,偶想你是见鬼了啦


顶起来

[shengli_liao]

什么错误，你打出来我们看看

[ian63]

错误代码~

[baoma2000]

查询不需要加上conn.commit()吧。
conn.prepareStatement("select * from t where a='?' and b='?'");肯定不行的。

没有报错，就是查不出数据，我怀疑是不是oracle jdbc或者数据库版本问题。

[baoma2000]

这是完整的代码

public static void main(String[] args) {
try {
Class.forName("oracle.jdbc.OracleDriver");
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@10.2.3.26:1521:test", "test", "test");
PreparedStatement st = null;
int i = 0;

st = conn.prepareStatement("select * from D90qx where f90yhbh=?");
st.setString(1, "f90yhbh");
i = getCount(st);

st = conn.prepareStatement("select * from D90qx");
i = getCount(st);

st = conn.prepareStatement("select * from D90qx where f90yhbh='f90yhbh' and f90zcbh='f90zcbh3'");
i = getCount(st);

st = conn.prepareStatement("select * from D90qx where f90yhbh=? and f90zcbh=?");
st.setString(1, "f90yhbh");
st.setString(2, "f90zcbh3");
//st.
i = getCount(st);

conn.close();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

private static int getCount(PreparedStatement st)
{
int i = 0;
try {
ResultSet rs = st.executeQuery();
while (rs.next())
{
String str1 = rs.getString(1);
String str2 = rs.getString(2);
i++;
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return i;
}

[huang3407]

select * from t where a=? and b=?
可以这样子吗？ select * from t where a=? and b=? and c=? and d=? 或者是select * from t where a=? && b=? &&c=? a&& d=?

[baoma2000]

我试了，也查不出来。

[herobjfu]

我也遇到了,但是不知道怎么解决

[herobjfu]

看看数据库里字段的类型,文档里这么说
Sets the designated parameter to the given Java String value. The driver converts this to an SQL VARCHAR or LONGVARCHAR value (depending on the argument's size relative to the driver's limits on VARCHAR values) when it sends it to the database. 有可能是这个原因

[herobjfu]

我的问题解决了,是数据库里空格,建议你看看你的数据里的字段类型