语句adodataset1.Filter :='mid(c,1,1)=1'
但提示错误“参数类型不正确类型,或者不可以在接受的范围之内,或与其它参数冲突”
为什么?不能使用mid函数?有没有哪位高手指点指点,非常感谢!
但提示错误“参数类型不正确类型,或者不可以在接受的范围之内,或与其它参数冲突”
为什么?不能使用mid函数?有没有哪位高手指点指点,非常感谢!
解决方案 »
- D2006中interbase admin控件组哪去了?
- 请教一个问题,在线等。。。。
- 问题解决一下
- 请问方法:procedure logined(baliasname:olevariant;var ayhbh:olevariant)在type library里的设置步骤,谢谢!
- 关于StringGrid的控制
- 请教"网格索引越界"的问题
- 关于c/s模式的问题
- delphi2010安装CoolControls的求助
- 急聘编程人员(希望斑竹不要删除此消息!谢谢!)
- 高手来呀!救命!
- win98下,窗体上Combobox控件较多时,运行报错:'A Call to an OS function failed',谁能解决重分相谢!!!
- 关于数据填充的问题。。各位帮帮忙吧,谢谢了
Operatoror function Example Supported by other datasets Comment
Comparisons
= State = 'CA' Yes
<> State <> 'CA' Yes
>= DateEntered >= '1/1/1998' Yes
<= Total <= 100,000 Yes
> Percentile > 50 Yes
< Field1 < Field2 Yes
BLANK State <> 'CA' or State = BLANK Yes Blank records do not appear unless explicitly included in the filter.
IS NULL Field1 IS NULL No
IS NOT NULL Field1 IS NOT NULL No
Logical operators
and State = 'CA' and Country = 'US' Yes
or State = 'CA' or State = 'MA' Yes
not not (State = 'CA') Yes
Arithmetic operators
+ Total + 5 > 100 Depends on driver Applies to numbers, strings, or date (time) + number.
- Field1 - 7 <> 10 Depends on driver Applies to numbers, dates, or date (time) - number.
* Discount * 100 > 20 Depends on driver Applies to numbers only.
/ Discount > Total / 5 Depends on driver Applies to numbers only.
String functions
Upper Upper(Field1) = 'ALWAYS' No
Lower Lower(Field1 + Field2) = 'josp' No
Substring Substring(DateFld,8) = '1998'Substring(DateFld,1,3) = 'JAN' No Value goes from position of second argument to end or number of chars in third argument. First char has position 1.
Trim Trim(Field1 + Field2)Trim(Field1, '-') No Removes third argument from front and back. If no third argument, trims spaces.
TrimLeft TrimLeft(StringField)TrimLeft(Field1, '$') <> '' No See Trim.
TrimRight TrimRight(StringField)TrimRight(Field1, '.') <> '' No See Trim.
DateTime functions
Year Year(DateField) = 2000 No
Month Month(DateField) <> 12 No
Day Day(DateField) = 1 No
Hour Hour(DateField) < 16 No
Minute Minute(DateField) = 0 No
Second Second(DateField) = 30 No
GetDate GetDate - DateField > 7 No Represents current date and time.
Date DateField = Date(GetDate) No Returns the date portion of a datetime value.
Time TimeField > Time(GetDate) No Returns the time portion of a datetime value.
Miscellaneous
Like Memo LIKE '%filters%' No Works like SQL-92 without the ESC clause. When applied to BLOB fields, FilterOptions determines whether case is considered.
In Day(DateField) in (1,7) No Works like SQL-92. Second argument is a list of values all with the same type.
* State = 'M*' Yes Wildcard for partial comparisons.
When applying ranges or filters, the client dataset still stores all of its records in memory. The range or filter merely determines which records are available to controls that navigate or display data from the client dataset.
那如果函数不支持的话,有没有其它的办法实现?
不知道还有没有其它的办法
我原来考虑过小虫的sql查询的办法,但我估计查询量大,速度会慢,所以采用filter。不知道有没有好的解决办法
没找到mid函数不要太钻牛角尖