与Access数据库结构有关的一些函数

与Access数据库结构有关的一些函数

//与数据库结构有关的一些函数

//1、动态改变字段名称

uses ComObj;

//Access

//TableName: 表名; OldColName: 原字段名; NewColName: 新字段名;

procedure RenameField(const TableName, OldColName, NewColName: string);

var

DB, Col: OleVariant;

begin

DB := CreateOleObject('ADOX.Catalog');

DB.ActiveConnection := ADOConnection1.ConnectionObject;

Col := CreateOleObject('ADOX.Column');

Col := DB.Tables[TableName].Columns[OldColName];

Col.Name := NewColName;

end;

//SQLServer

procedure RenameField(const TableName, OldColName, NewColName: string);

begin

with ADOCommand1 do

begin

CommandText := 'EXEC sp_rename ''' + TableName + '.' + OldColName +

''',''' + NewColName + ''',''COLUMN'';';

Excute;

end;

end;

2、取得 Access 库中的表结构

type

TTableDef = record

Name,

DateCreated,

LastUpdated,

Description: string;

end;

TTableDefs = array of TTableDef;

procedure GetTableDefs(const DBName: string; out TableDefs: TTableDefs);

var

DBEngine, DB: OleVariant;

I: Longint;

begin

try

DBEngine := CreateOleObject('DAO.DBEngine.36');

DB := DBEngine.OpenDatabase(DBName);

SetLength(TableDefs, Longint(DB.TableDefs.Count));

for I := Low(TableDefs) to High(TableDefs) do

begin

TableDefs[I].Name := DB.TableDefs[I].Name;

TableDefs[I].DateCreated := DB.TableDefs[I].DateCreated;

TableDefs[I].LastUpdated := DB.TableDefs[I].LastUpdated;

try

TableDefs[I].Description := DB.TableDefs[I].Properties['Description'].Value;

except

TableDefs[I].Description := '';

end;

end;

finally

DB := Unassigned;

DBEngine := Unassigned;

end;

end;

3、取得 Access 表中的字段结构

type

TFieldDef = record

Name: string;

Types,

Size: Longint;

Description: string;

end;

TFieldDefs = array of TFieldDef;

procedure GetFieldDefs(const DBName, TableName: string; out FieldDefs: TFieldDefs);

var

DBEngine, DB: OleVariant;

I: Longint;

begin

try

DBEngine := CreateOleObject('DAO.DBEngine.36');

DB := DBEngine.OpenDatabase(DBName);

SetLength(FieldDefs, Longint(DB.TableDefs[TableName].Fields.Count));

for I := Low(FieldDefs) to High(FieldDefs) do

begin

FieldDefs[I].Name := DB.TableDefs[TableName].Fields[I].Name;

FieldDefs[I].Types := DB.TableDefs[TableName].Fields[I].Type;

FieldDefs[I].Size := DB.TableDefs[TableName].Fields[I].Size;

try

FieldDefs[I].Description := DB.TableDefs[TableName].Fields[I].Properties['Description'].Value;

except

FieldDefs[I].Description := '';

end;

end;

finally

DB := Unassigned;

DBEngine := Unassigned;

end;

end;

打印MSAccess2000数据库结构信息

阅读：576次 时间：2003-08-19 00:00:00 字体：[大
中 小]

下列程序可以打印 MS Access 2000 数据库结构信息

若有问题请联系: xinsheng_chang@163.com

0710-6545726

ReportControl、tvAPIThing 单元可在网上找，也可以与作者联系。

unit GetDBStruInfo;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, DB, ADODB, ExtCtrls, ReportControl, Grids, DBGrids,
tvAPIThing, Buttons;

type
TGetDBStruInfoFrm = class(TForm)
ADOConnection1: TADOConnection;
ListBox1: TListBox;
Panel1: TPanel;
Button1: TButton;
ADOTable1: TADOTable;
ADOTable2: TADOTable;
ADOConnection2: TADOConnection;
ReportRunTime1: TReportRunTime;
Button2: TButton;
OpenDialog1: TOpenDialog;
BitBtn1: TBitBtn;
Bevel1: TBevel;
Label1: TLabel;
Label2: TLabel;
Button3: TButton;
tvAPIThing1: TtvAPIThing;
Image1: TImage;
procedure Button1Click(Sender: TObject);
function GetFieldType(ly: TFieldType): string;
function GetFieldBZ(ly: TFieldType): string;
procedure Button2Click(Sender: TObject);
procedure BitBtn1Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
GetDBStruInfoFrm: TGetDBStruInfoFrm;
dbnamevar: string;
implementation

{$R *.dfm}

procedure TGetDBStruInfoFrm.Button1Click(Sender: TObject);
var
i, j, k, p: integer;
mytextfile: TextFile;
begin
ADOConnection1.Connected := false;
OpenDialog1.Title := '请选择数据库';
OpenDialog1.Filter := 'MS Access files (*.mdb)|*.mdb';

if not OpenDialog1.Execute then
exit;
if OpenDialog1.FileName = '' then
exit;
ADOConnection1.ConnectionString :=
'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=' +
OpenDialog1.FileName;
dbnamevar := OpenDialog1.FileName;
Label2.Caption := dbnamevar;
Refresh;
AssignFile(mytextfile, ExtractFilePath(Application.exename) +
'DBStruInfo.txt');
ReWrite(mytextfile);
writeln(mytextfile, '序号,', '名称,', '字段类型,', '字段宽度,', '备注');
screen.cursor := crHourGlass;
try
ADOConnection1.GetTableNames(listbox1.Items, false);
j := listbox1.Items.Count;
for i := 0 to j - 1 do
begin
ADOTable1.Active := false;
writeln(mytextfile, 'B', 100 + i + 1, ',', listbox1.items[i]);
ADOTable1.TableName := '[' + listbox1.items[i] + ']';
ADOTable1.Active := true;
p := ADOTable1.FieldCount;
for k := 0 to p - 1 do
begin
writeln(mytextfile, 'B', 100 + i + 1, 'ZD', 100 + k + 1, ',',
ADOTable1.Fields[K].FieldName,
',', GetFieldType(ADOTable1.Fields[k].DataType), ',',
ADOTable1.Fields[k].Size,
',', GetFieldBZ(ADOTable1.Fields[k].DataType));
end;
end;
Button2.Enabled := true;
finally
closefile(mytextfile);
ADOConnection1.Connected := false;
screen.cursor := crDefault;
SHOWMESSAGE('完成！');
end;
end;

function TGetDBStruInfoFrm.GetFieldType(ly: TFieldType): string;
begin
case ly of
ftUnknown: Result := 'Unknown';
ftString: Result := 'Character or string';
ftSmallint: Result := '16-bit integer';
ftInteger: Result := '32-bit integer';
ftWord: Result := '16-bit unsigned integer';
ftBoolean: Result := 'Boolean';
ftFloat: Result := 'Floating-point numeric';
ftCurrency: Result := 'Money';
ftBCD: Result := 'Binary-Coded Decimal';
ftDate: Result := 'Date';
ftTime: Result := 'Time';
ftDateTime: Result := 'Date and time';
ftBytes: Result := 'Fixed number of bytes';
ftVarBytes: Result := 'Variable number of bytes';
ftAutoInc: Result := 'Auto-incrementing 32-bit integer counter';
ftBlob: Result := 'Binary Large OBject';
ftMemo: Result := 'Text memo';
ftGraphic: Result := 'Bitmap';
ftFmtMemo: Result := 'Formatted text memo';
ftParadoxOle: Result := 'Paradox OLE';
ftDBaseOle: Result := 'dBASE OLE';
ftTypedBinary: Result := 'Typed binary';
ftCursor: Result :=
'Output cursor from an Oracle stored procedure (TParam only)';
ftFixedChar: Result := 'Fixed character';
ftWideString: Result := 'Wide string';
ftLargeint: Result := 'Large integer';
ftADT: Result := 'Abstract Data Type';
ftArray: Result := 'Array';
ftReference: Result := 'REF';
ftDataSet: Result := 'DataSet';
ftOraBlob: Result := 'BLOB in Oracle 8 tables';
ftOraClob: Result := 'CLOB in Oracle 8 tables';
ftVariant: Result := 'Data of unknown or undetermined type';
ftInterface: Result := 'References to interfaces';
ftIDispatch: Result := 'References to IDispatch interfaces';
ftGuid: Result := 'globally unique identifier (GUID) values';
ftTimeStamp: Result := 'Date and time field accessed through dbExpress';
ftFMTBcd: Result :=
'Binary-Coded Decimal field that is too large for ftBCD';
else
Result := '不知道';
end;
end;

function TGetDBStruInfoFrm.GetFieldBZ(ly: TFieldType): string;
begin
case ly of
ftUnknown: Result := 'Unknown or undetermined';
ftString: Result := 'Character or string field';
ftSmallint: Result := '16-bit integer field';
ftInteger: Result := '32-bit integer field';
ftWord: Result := '16-bit unsigned integer field';
ftBoolean: Result := 'Boolean field';
ftFloat: Result := 'Floating-point numeric field';
ftCurrency: Result := 'Money field';
ftBCD: Result :=
'Binary-Coded Decimal field that can be converted to Currency type without a loss of precision';
ftDate: Result := 'Date field';
ftTime: Result := 'Time field';
ftDateTime: Result := 'Date and time field';
ftBytes: Result := 'Fixed number of bytes (binary storage)';
ftVarBytes: Result := 'Variable number of bytes (binary storage)';
ftAutoInc: Result := 'Auto-incrementing 32-bit integer counter field';
ftBlob: Result := 'Binary Large OBject field';
ftMemo: Result := 'Text memo field';
ftGraphic: Result := 'Bitmap field';
ftFmtMemo: Result := 'Formatted text memo field';
ftParadoxOle: Result := 'Paradox OLE field';
ftDBaseOle: Result := 'dBASE OLE field';
ftTypedBinary: Result := 'Typed binary field';
ftCursor: Result :=
'Output cursor from an Oracle stored procedure (TParam only)';
ftFixedChar: Result := 'Fixed character field';
ftWideString: Result := 'Wide string field';
ftLargeint: Result := 'Large integer field';
ftADT: Result := 'Abstract Data Type field';
ftArray: Result := 'Array field';
ftReference: Result := 'REF field';
ftDataSet: Result := 'DataSet field';
ftOraBlob: Result := 'BLOB fields in Oracle 8 tables';
ftOraClob: Result := 'CLOB fields in Oracle 8 tables';
ftVariant: Result := 'Data of unknown or undetermined type';
ftInterface: Result := 'References to interfaces (IUnknown)';
ftIDispatch: Result := 'References to IDispatch interfaces';
ftGuid: Result := 'globally unique identifier (GUID) values';
ftTimeStamp: Result := 'Date and time field accessed through dbExpress';
ftFMTBcd: Result :=
'Binary-Coded Decimal field that is too large for ftBCD';
else
Result := '不知道';
end;

end;

procedure TGetDBStruInfoFrm.Button2Click(Sender: TObject);
begin
ADOConnection2.Connected := false;
ADOConnection2.ConnectionString := 'Provider=MSDASQL.1;' +
'Persist Security Info=False;' +
'Extended Properties="' +
'DefaultDir=' + ExtractFiledir(Application.exename) + ';' +
'Driver={Microsoft Text Driver (*.txt; *.csv)};' +
'DriverId=27;Extensions=txt,csv,tab,asc;FIL=text;' +
'FILEDSN=' + ExtractFiledir(Application.exename) + '\misdbstrue;' +
'MaxBufferSize=2048;MaxScanRows=25;PageTimeout=5;' +
'SafeTransactions=0;Threads=3;UID=admin;UserCommitSync=Yes;"';
if not ADOTable2.Active then
ADOTable2.Active := true;
SetCurrentDir(ExtractFiledir(Application.exename));
ADOTable2.DisableControls;
ReportRunTime1.ReportFile := ExtractFilePath(Application.exename) +
'misdbstrueinfo.ept';
with ReportRunTime1 do
begin
EnableEdit := True;
SetDataSet('d1', ADOTable2); //设置报表模板中的数据集变量名
SetVarValue('DBName', dbnamevar); //设置报表模板中的字符变量内容
//      SetVarValue('GSNAME',GSNameVar);                //设置报表模板中的字符变量内容
//      SetVarValue('code',Code1);
PrintPreview(True); //打印
end;
ADOTable2.DisableControls;
ADOTable2.Active := false;
ADOConnection2.Connected := false;
end;

procedure TGetDBStruInfoFrm.BitBtn1Click(Sender: TObject);
begin
close;
end;

procedure TGetDBStruInfoFrm.Button3Click(Sender: TObject);
var
s1, s2: string;
x: TFixedFileInfo;
begin
x := tvAPIThing1.FileInfo(Application.ExeName);
s1 := tvAPIThing1.GetFileInformation(Application.ExeName, 'InternalName'); //
s2 := Application.Title + #13#10 +
'Version: ' + IntToStr(x.wFileVersionLS) + '.'
+ IntToStr(x.wFileVersionMS) +
' (Build: ' + IntToStr(x.wProductVersionMS) + ') Release: ' +
IntToStr(x.wProductVersionLS) + #13#10 +
tvAPIThing1.GetFileInformation(Application.ExeName, 'CompanyName')
+ #13#10 + 'E-mail：xinsheng_chang@163.com';
tvAPIThing1.ShellAbout(s1, s2);
end;

end.

Public Sub getTables()
Dim rs As New ADODB.Recordset
Dim conn As ADODB.Connection
Dim sSql As String

Set conn = CurrentProject.Connection
sSql = "select id,Name from MSysObjects where Type=1 and flags=0"
rs.Open sSql, conn
Do While Not rs.EOF
Debug.Print "****"; rs.Fields("Name").Value; "****************"
getTableColumns rs.Fields("Name").Value
rs.MoveNext
Loop
rs.Close
Set rs = Nothing
Set conn = Nothing

End Sub

Public Sub getTableColumns(sTableName As String)
Dim rs As New ADODB.Recordset
Dim conn As ADODB.Connection
Dim fld As ADODB.Field

Set conn = CurrentProject.Connection
rs.Open sTableName, conn, , , adCmdTable

For Each fld In rs.Fields
Debug.Print fld.Name, sFldType(fld.Type), fld.NumericScale, fld.Precision

Next

rs.Close
Set rs = Nothing
Set conn = Nothing

End Sub

lString,lTableName:TStrings;

//-----------获取表名信息-------------

lString:=TStringList.Create;

lTableName:=TStringList.Create;

DM_Conn.con_Access.GetTableNames(lString,True);

for i:=0 to lString.Count-1 do

begin

if (lString.Strings[i]<>'MSysACEs')

and (lString.Strings[i]<>'MSysObjects')

and (lString.Strings[i]<>'MSysQueries')

and (lString.Strings[i]<>'MSysRelationships') then

lTableName.Add(lString.Strings[i]);

end;

Access中Data_type的说名

switch (data_type) {

//case常量 值 说明

//case 0x2000

// :p = AdArray //（不适用于 ADOX。） 0x2000 一个标志值，通常与另一个数据类型常量组合，指示该数据类型的数组。

case 20: p = "adBigInt 20 指示一个八字节的有符号整数 (DBTYPE_I8)。";

case 128: p = "adBinary 128 指示一个二进制值 (DBTYPE_BYTES)。";

case 11: p = "adBoolean 指示一个布尔值 (DBTYPE_BOOL)。";

case 8: p = "adBSTR 8 指示以 Null 终止的字符串 (Unicode) (DBTYPE_BSTR)。";

case 136: p = "adChapter 136 指示一个四字节的子集值，标识子行集合中的行 (DBTYPE_HCHAPTER)。";

case 129: p = "adChar129 指示一个字符串值 (DBTYPE_STR)。";

case 6: p = "adCurrency 6 指示一个货币值 (DBTYPE_CY)。货币是一个定点数字，小数点右侧有四位数字。该值存储为八字节、范围为 10,000 的有符号整数。";

case 7: p = "adDate 7 指示日期值 (DBTYPE_DATE)。日期保存为双精度数，数字的整数部分是从 1899 年 12 月 30 日算起的天数，小数部分是一天当中的片段时间。";

case 133: p = "adDBDate 133 指示日期值 (yyyymmdd) (DBTYPE_DBDATE)。";

case 134: p = "adDBTime 134 指示时间值 (hhmmss) (DBTYPE_DBTIME)。";

case 135: p = "adDBTimeStamp 135 指示日期/时间戳（yyyymmddhhmmss 加十亿分之一的小数）(DBTYPE_DBTIMESTAMP)。";

case 14: p = "adDecimal 14 指示具有固定精度和范围的确切数字值 (DBTYPE_DECIMAL)。";

case 5: p = "adDouble 5 指示一个双精度浮点值 (DBTYPE_R8)。";

case 0: p = "adEmpty 0 指定没有值 (DBTYPE_EMPTY)。";

case 10: p = "adError 10 指示一个 32 位的错误代码 (DBTYPE_ERROR)。";

case 64: p = "adFileTime 64 指示一个 64 位的值，表示从 1601 年 1 月 1 日开始的 100 个十亿分之一秒间隔的数量 (DBTYPE_FILETIME)。";

case 72: p = "adGUID 72 指示全局唯一标识符 (GUID) (DBTYPE_GUID)。";

case 9: p = "adIDispatch 9 指示指向 COM 对象上 IDispatch 接口的指针 (DBTYPE_IDISPATCH)。";

//注意 ADO 目前不支持这种数据类型。使用它可能导致不可预料的结果。 case 3: p = " adInteger 3 指示一个四字节的有符号整数 (DBTYPE_I4)。";

case 13: p = "adIUnknown 13 指示指向 COM 对象上 IUnknown 接口的指针 (DBTYPE_IUNKNOWN)。";

//注意 ADO 目前不支持这种数据类型。使用它可能导致不可预料的结果。 case 205: p = "adLongVarBinary 205 指示一个长二进制值（仅限于 Parameter 对象）。";

case 201: p = " adLongVarChar 201 指示一个长字符串值（仅限于 Parameter 对象）。";

case 203: p = "adLongVarWChar 203 指示一个以 Null 终止的长 Unicode 字符串值（仅限于 Parameter 对象）。";

case 131: p = "adNumeric 131 指示具有固定精度和范围的确切数字值 (DBTYPE_NUMERIC)。";

case 138: p = "adPropVariant 138 指示一个 Automation PROPVARIANT (DBTYPE_PROP_VARIANT)。";

case 4: p = "adSingle 4 指示一个单精度浮点值 (DBTYPE_R4)。";

case 2: p = "adSmallInt 2 指示一个双字节的有符号整数 (DBTYPE_I2)。";

case 16: p = "adTinyInt 16 指示一个单字节的有符号整数 (DBTYPE_I1)。";

case 21: p = " adUnsignedBigInt 21 指示一个八字节的无符号整数 (DBTYPE_UI8)。";

case 19: p = "adUnsignedInt 19 指示一个四字节的无符号整数 (DBTYPE_UI4)。";

case 18: p = "adUnsignedSmallInt 18 指示一个双字节的无符号整数 (DBTYPE_UI2)。";

case 17: p = "adUnsignedTinyInt 17 指示一个单字节的无符号整数 (DBTYPE_UI1)。";

case 132: p = "adUserDefined 132 指示一个用户定义的变量 (DBTYPE_UDT)。";

case 204: p = "adVarBinary 204 指示一个二进制值（仅限于 Parameter 对象）。";

case 200: p = "adVarChar 200 指示一个字符串值（仅限于 Parameter 对象）。";

case 12: p = "adVariant 12 指示一个 Automation Variant (DBTYPE_VARIANT)。";

//注意 ADO 目前不支持这种数据类型。使用它可能导致不可预料的结果。 case 139: p = "adVarNumeric 139 指示一个数字值（仅限于 Parameter 对象）。";

case 202: p = "adVarWChar 202 指示一个以 Null 终止的 Unicode 字符串（仅限于 Parameter 对象）。";

case 130: p = "adWChar 130 指示一个以 Null 终止的 Unicode 字符串 (DBTYPE_WSTR)。";

}

DELPHI中操作ACCESS数据库(建立.mdb文件,压缩数据库)

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.

//   动态创建.mdb数据库文件
procedure   TMainForm.CreateDynamicDatabase(filename:   string);
var
CreateAccess:   OleVariant;
begin
CreateAccess   :=   CreateOleObject( 'ADOX.Catalog ');
CreateAccess.Create( 'Provider=Microsoft.Jet.OLEDB.4.0;Data   Source= '   +   filename
+    ';   Jet   OLEDB:Database   Password=xyz ');
end;

//   创建场地信息表
procedure   TMainForm.CreateTableCDXX;
begin
with   ADOQuery1   do
begin
Close;
SQL.Clear;
SQL.Add( 'Create   Table   CDXX( ');
SQL.Add( 'CD   char(5)   not   null,    ');
SQL.Add( 'RQ   date   not   null,    ');
SQL.Add( 'ZSR   money   default   0   not   null,    ');
SQL.Add( 'ZZC   money   default   0   not   null,    ');
SQL.Add( 'ZYY   money   default   0   not   null,    ');
SQL.Add( 'PRIMARY   KEY   (CD)) ');
ExecSQL;
end;
end;

//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;';

//=============================================================================
// 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(result);
end;

//=============================================================================
// 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;

//=============================================================================
// 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;

DELPHI对ACCESS表结构操作
-
新建表： create table [表名] ( [自动编号字段] int IDENTITY (1,1) PRIMARY KEY , [字段1] nVarChar(50) default ''默认值'' null , [字段2] ntext null , [字段3] datetime, [字段4] money null , [字段5] int default 0, [字段6] Decimal (12,4) default 0, [字段7] image null , ) 删除表： Drop table [表名]
插入数据： INSERT INTO [表名] (字段1,字段2) VALUES (100,''51WINDOWS.NET'') 删除数据： DELETE FROM [表名] WHERE [字段名]>100 更新数据： UPDATE [表名] SET [字段1] = 200,[字段2] = ''51WINDOWS.NET'' WHERE [字段三] = ''HAIWA'' 新增字段： ALTER TABLE [表名] ADD [字段名] NVARCHAR (50) NULL 删除字段： ALTER TABLE
[表名] DROP COLUMN [字段名] 修改字段： ALTER TABLE [表名] ALTER COLUMN [字段名] NVARCHAR (50) NULL 重命名表：(Access 重命名表，请参考文章：在Access数据库中重命名表) sp_rename ''表名'', ''新表名'', ''OBJECT'' 新建约束： ALTER TABLE [表名] ADD CONSTRAINT 约束名 CHECK ([约束字段] <= ''2000-1-1'') 删除约束： ALTER TABLE [表名]
DROP CONSTRAINT 约束名新建默认值 ALTER TABLE [表名] ADD CONSTRAINT 默认值名 DEFAULT ''51WINDOWS.NET'' FOR [字段名] 删除默认值 ALTER TABLE [表名] DROP CONSTRAINT 默认值名另外以上的只是SQL的语法在 ACCESS 下大部份也都是一样的项一项查阅,并经自己使用验证,确认在access 数据库中添加自动编号字段使用以下方法比较合适: create table 数据表名称 (id counter constraint
primarykey primary key) 需要注意的地方是:第二个primary中间有空格,另外,关键字不区分大小写. 另外自己最近发现的一种方法是: sql="create table mytb (id autoincrement(25,1) primary key,age int)" sql2="create table testtb (id autoincrement,age int,email char, primary key (id))" 其中在access中,autoincrement为自动编号类型字段,(25,1)分别为初始值及步长值,如果不写的话,默认是1,1,primary
key指定了主键,以上示例,两种指定方法都可以
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.

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;

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;
同样功能的SQL语句在ACCESS中应该是
UPDATE Tab1 a,Tab2 b
SET a.Name = b.Name
WHERE a.ID = b.ID;
即:ACCESS中的UPDATE语句没有FROM子句,所有引用的表都列在UPDATE关键字后.
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;

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.

在ACCESS中访问其它ODBC数据源
下例在ACCESS中查询SQLSERVER中的数据
SELECT * FROM Tab1 IN [ODBC]
[ODBC;Driver=SQL Server;UID=sa;PWD=;Server=127.0.0.1;DataBase=Demo;]
外部数据源连接属性的完整参数是:
[ODBC;DRIVER=driver;SERVER=server;DATABASE=database;UID=user;PWD=password;]
其中的DRIVER=driver可以在注册表中的
HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBCINST.INI\
中找到

ACCESS支持子查询

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

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)]));

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.