简单问题，送分，如何返回用Query查询得到的记录条数？(20分)

X

xoenice

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• 2002-11-08

• #1

这是我的源代码：
Query1.Active:=false;
Query1.SQL.Clear;
Query1.SQL.Add('select * from Tb_JKinfo where JK_ID=12');
Query1.Prepare;
Query1.Open;

i:= Query1.RecordCount;
showmessage(inttostr(i));
返回值始终是-1;

在对应的DBGrid中显示有记录。

 

Y

yaya8163

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• 2002-11-08

• #2

SELECT之后,先query.last,再query.first,就可以得到正确的recordcount.

 

土

土土

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• 2002-11-08

• #3

跟踪一下

 

J

jrq

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• 2002-11-08

• #4

加上如下语句测试一下，看看毛病出在哪里？
....
.....
Query1.Open;

if Not Query1.IsEmpty then
begin
i:= Query1.RecordCount;
showmessage(inttostr(i));
end
else
showmessage('没有找到任何记录');

 

B

bes96261

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• 2002-11-09

• #5

你的Select語句中可能包括一些特殊的字段類型，如圖形字段等

 

W

Wind

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• 2002-11-09

• #6

看一下RecordCount的说明吧
As implemented in TDataSet, RecordCount is always -1.
Ordinarily an application does not access RecordCount at the TDataSet level.
Instead a redeclared and implemented RecordCount property in a descendant
class is accessed. RecordCount provides a fallback property for derived
dataset classes that do not reimplement the property access method.

 

K

kelaizi

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• 2002-11-10

• #7

上面的英文解释说得很清楚了，不能在tdataset组件中获得recordcount的值，只能在他的继承
类中获得。

 

U

ugvanxk

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• 2002-11-10

• #8

'select count(*) from Tb_JKinfo where JK_ID=12'

 

M

mlc67

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• 2002-11-11

• #9

在我机器上试没毛病啊。我是这样写的：

Query1.Active:=false;
Query1.SQL.Clear;
Query1.SQL.Add('select * from ta_authority where authid=2 ');
Query1.Prepare;
Query1.Open;
showmessage(inttostr(Query1.RecordCount));

 

雪

雪中漫步

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• 2002-11-11

• #10

上面的老兄，你们的英文翻译的没错，可是人家楼主可是用的query啊，还不是
Tdataset的继承类吗，所以你们的解释不成立！
我想楼主用的是BDE吧，看看delphi的帮助，用bde时，recorcount只适用于
padox和DBASE "Generally, an application should only use RecordCount with
Paradox and dBASE tables."
如果你用的是sql server等其他大型数据库，就会出现-1的情况，而且有时也会得到
正确的条数，用ado好象还没发现这样的问题

 

X

xoenice

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• 2002-11-12

• #11

结贴