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//=============================================================================
// Procedure: GetTempPathFileName
// Author : ysai
// Date : 2003-01-27
// Arguments: (None)
// Result : string
//=============================================================================
function GetTempPathFileName():string;
//取得臨時文件名
var
SPath,Sfile&:array [0..254] of char;
begin
GetTempPath(254,SPath);
GetTempFileName(SPath,'~SM',0,SFile);
result:=SFile;
DeleteFile(PChar(result));
end; www.iTbulo.com0sJZ0
//=============================================================================
// Procedure: CreateAccessFile
// Author : ysai
// Date : 2003-01-27
// Arguments: FileName:String;PassWord:string=''
// Result : boolean
//=============================================================================
function CreateAccessFile(FileName:String;PassWord:string=''):boolean;
//建立Access文件,如果文件存在則失敗
var
STempFileName:string;
vCatalog:OleVariant;
begin
STempFileName:=GetTempPathFileName;
try
vCatalog:=CreateOleObject('ADOX.Catalog');
vCatalog.Create(format(SConnectionString,[STempFileName,PassWord]));
result:=CopyFile(PChar(STempFileName),PChar(FileName),True);
DeleteFile(STempFileName);
except
result:=false;
end;
end; www.iTbulo.com0sJZ0
//=============================================================================
// Procedure: CompactDatabase
// Author : ysai
// Date : 2003-01-27
// Arguments: AFileName,APassWord:string
// Result : boolean
//=============================================================================
function CompactDatabase(AFileName,APassWord:string):boolean;
//壓縮與修復數據庫,覆蓋源文件
var
STempFileName:string;
vJE:OleVariant;
begin
STempFileName:=GetTempPathFileName;
try
vJE:=CreateOleObject('JRO.JetEngine');
vJE.CompactDatabase(format(SConnectionString,[AFileName,APassWord]),
format(SConnectionString,[STempFileName,APassWord]));
result:=CopyFile(PChar(STempFileName),PChar(AFileName),false);
DeleteFile(STempFileName);
except
result:=false;
end;
end; www.iTbulo.com0sJZ0
//=============================================================================
// Procedure: ChangeDatabasePassword
// Author : ysai
// Date : 2003-01-27
// Arguments: AFileName,AOldPassWord,ANewPassWord:string
// Result : boolean
//=============================================================================
function ChangeDatabasePassword(AFileName,AOldPassWord,ANewPassWord:string):boolean;
//修改ACCESS數據庫密碼
var
STempFileName:string;
vJE:OleVariant;
begin
STempFileName:=GetTempPathFileName;
try
vJE:=CreateOleObject('JRO.JetEngine');
vJE.CompactDatabase(format(SConnectionString,[AFileName,AOldPassWord]),
format(SConnectionString,[STempFileName,ANewPassWord]));
result:=CopyFile(PChar(STempFileName),PChar(AFileName),false);
DeleteFile(STempFileName);
except
result:=false;
end;
end; www.iTbulo.com0sJZ0
2.ACCESS中使用SQL語句應注意的地方及幾點技巧
以下SQL語句在ACCESS XP的查詢中測試通過
建表:
Create Table Tab1 (
ID Counter,
Name string,
Age integer,
[Date] DateTime);
技巧:
自增字段用 Counter 聲明.
字段名為關鍵字的字段用方括號[]括起來,數字作為字段名也可行. www.iTbulo.com0sJZ0
建立索引:
下面的語句在Tab1的Date列上建立可重復索引
Create Index iDate ON Tab1 ([Date]);
完成后ACCESS中字段Date索引屬性顯示為 - 有(有重復).
下面的語句在Tab1的Name列上建立不可重復索引
Create Unique Index iName ON Tab1 (Name);
完成后ACCESS中字段Name索引屬性顯示為 - 有(無重復).
下面的語句刪除剛才建立的兩個索引
Drop Index iDate ON Tab1;
Drop Index iName ON Tab1; www.iTbulo.com0sJZ0
ACCESS與SQLSERVER中的UPDATE語句對比:
SQLSERVER中更新多表的UPDATE語句:
www.iTbulo.com0sJZ0
訪問多個不同的ACCESS數據庫-在SQL中使用In子句:
Select a.*,b.* From Tab1 a,Tab2 b In 'DB2.mdb' Where a.ID=b.ID;
上面的SQL語句查詢出當前數據庫中Tab1和db2.mdb(當前文件夾中)中Tab2以ID為關聯的所有記錄.
缺點-外部數據庫不能帶密碼.
補充:看到ugvanxk在一貼中的答復,可以用
Select * from [c:aaa.mdb;pwd=1111].table1;
ACCESS XP測試通過 www.iTbulo.com0sJZ0
在ACCESS中訪問其它ODBC數據源
下例在ACCESS中查詢SQLSERVER中的數據
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ACCESS支持子查詢 www.iTbulo.com0sJZ0
ACCESS支持外連接,但不包括完整外部聯接,如支持
LEFT JOIN 或 RIGHT JOIN
但不支持
FULL OUTER JOIN 或 FULL JOIN www.iTbulo.com0sJZ0
ACCESS中的日期查詢
注意:ACCESS中的日期時間分隔符是#而不是引號
Select * From Tab1 Where [Date]>#2002-1-1#;
在DELPHI中我這樣用
SQL.Add(Format(
'Select * From Tab1 Where [Date]>#%s#;',
[DateToStr(Date)])); www.iTbulo.com0sJZ0
ACCESS中的字符串可以用雙引號分隔,但SQLSERVER不認,所以為了遷移方便和兼容, 建議用單引號作為字符串分隔符.www.iTbulo.com0sJZ0