以下代码在WIN2K,D6,MDAC2.6下测试通过,
编译好的程序在WIN98第二版无Access环境下运行成功.
//在之前uses ComObj,ActiveX
//声明连接字符串
Const
SConnectionString = 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=%s;'
+'Jet OLEDB:Database Password=%s;';
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//=============================================================================
// Procedure: GetTempPathFileName
// Author : ysai
// Date : 2003-01-27
// Arguments: (None)
// Result : string
//=============================================================================
function GetTempPathFileName():string;
//取得临时文件名
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，如果文件存在则失败
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;
//压缩与修复数据库,覆盖源文件
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数据库密码
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语句应注意的地方及几点技巧
以下SQL语句在Access XP的查询中测试通过
建表:
Create Table Tab1 (
ID Counter,
Name string,
Age integer,
[Date] DateTime);
技巧:
自增字段用 Counter 声明.
字段名为关键字的字段用方括号[]括起来,数字作为字段名也可行. www.iTbulo.com0sJZ0
建立索引:
下面的语句在Tab1的Date列上建立可重复索引
Create Index iDate ON Tab1 ([Date]);
完成后Access中字段Date索引属性显示为 - 有(有重复).
下面的语句在Tab1的Name列上建立不可重复索引
Create Unique Index iName ON Tab1 (Name);
完成后Access中字段Name索引属性显示为 - 有(无重复).
下面的语句删除刚才建立的两个索引
Drop Index iDate ON Tab1;
Drop Index iName ON Tab1; www.iTbulo.com0sJZ0
Access与SQLSERVER中的UPDATE语句对比:
SQLSERVER中更新多表的UPDATE语句:
UPDATE Tab1
SET a.Name = b.Name
FROM Tab1 a,Tab2 b
WHERE a.ID = b.ID;
SET a.Name = b.Name
WHERE a.ID = b.ID;
上例中如果Tab2可以不是一个表,而是一个查询,例:
UPDATE Tab1 a,(Select ID,Name From Tab2) b
SET a.Name = b.Name
WHERE a.ID = b.ID;
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访问多个不同的Access数据库-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语句查询出当前数据库中Tab1和DB2.mdb(当前文件夹中)中Tab2以ID为关联的所有记录.
缺点-外部数据库不能带密码.
补充:看到ugvanxk在一贴中的答复,可以用
Select * from [c:\aa\a.mdb;pwd=1111].table1;
Access XP测试通过 www.iTbulo.com0sJZ0
在Access中访问其它ODBC数据源
下例在Access中查询SQLSERVER中的数据
其中的DRIVER=driver可以在注册表中的
HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBCINST.INI\
中找到
异构数据库之间导数据参见 碧血剑
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Access支持子查询 www.iTbulo.com0sJZ0
Access支持外连接,但不包括完整外部联接,如支持
LEFT JOIN 或 RIGHT JOIN
但不支持
FULL OUTER JOIN 或 FULL JOIN www.iTbulo.com0sJZ0
Access中的日期查询
注意:Access中的日期时间分隔符是#而不是引号
Select * From Tab1 Where [Date]>#2002-1-1#;
在DELPHI中我这样用
SQL.Add(Format(
'Select * From Tab1 Where [Date]>#%s#;',
[DateToStr(Date)])); www.iTbulo.com0sJZ0
Access中的字符串可以用双引号分隔,但SQLSERVER不认,所以为了迁移方便和兼容, 建议用单引号作为字符串分隔符.www.iTbulo.com0sJZ0