关于实例讲解Oracle到SQL Server主键迁移的讲解

ADOConnOrcale: TADOConnection; //连接Oracle 
ADOConnSQLServer: TADOConnection; //连接SQL Server 
O1: TADOQuery; //连接Oracle 
S1: TADOQuery; //连接SQL Server 
S2: TADOQuery; //连接SQL Server 
ProgressBar1: TProgressBar; //进度条 
Memo1: TMemo; //显示出错信息 
EdtServer: TEdit; //服务器 
EdtDataBase: TEdit; //数据库名称 
EdtUser: TEdit; //用户名 
EdtPass: TEdit; //口令 
Button1: TButton; //执行按钮 
//常量 
const 
ORAConnStr='Provider=MSDAORA.1;Data Source=%S;User ID=%S;PassWord=%S;Persist Security 
Info=True'; 
SQLConnStr='Provider=SQLOLEDB.1;Data Source=%S;Initial Catalog=%S;User ID=%S;Password=%S;
Persist Security Info=False'; 
在执行前先进行Oracle和SQL Server数据库的连接。 

ADOConnOrcale.ConnectionString :=Format(ORAConnStr,[trim(EdtDataBase.Text), 
trim(EdtUser.Text),trim(EdtPass.Text)]); 
try 
ADOConnOrcale.Open; 
MsgBox('Oracle数据库连接成功!'); 
Except 
MsgBox('Oracle数据库连接失败!'); 
end; 

ADOConnSQLServer.ConnectionString :=Format(SQLConnStr,[trim(EdtServer.Text), 
trim(EdtDataBase.Text),trim(EdtUser.Text),trim(EdtPass.Text)]); 
try 
ADOConnSQLServer.Open; 
MsgBox('SQL Server数据库连接成功!') 
except 
MsgBox('SQL Server数据库连接失败!'); 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
var 
i:Integer; 
FieldN, tableN, fieldM,aa:String; 
begin 
if Not ADOConnOrcale.Connected then 
begin 
MsgBox('请先连接Oracle数据库!'); 
exit; 
end; 
if not ADOConnSQLServer.Connected then 
begin 
MsgBox('请先连接SQL Server数据库!'); 
exit; 
end; 
Screen.Cursor :=crHourGlass; 
try 
o1.Close; 
O1.SQL.Clear; 
//取oracle表用户budget的所有主键约束信息 
o1.SQL.Text :=' select a.CONSTRAINT_NAME,a.CONSTRAINT_TYPE,a.TABLE_NAME, b.COLUMN_NAME,
b.position '+ 
' from USER_CONSTRAINTS a,USER_CONS_COLUMNS b where a.CONSTRAINT_NAME=b.CONSTRAINT_NAME '+ 
' and a.table_name=b.table_name and constraint_type=''P'' and a.owner=b.owner '+ 
' and lower(a.owner)=''budget'' order by a.table_name,b.position '; 
O1.open; 
tableN:=''; 
O1.First; 
ProgressBar1.Max:=O1.RecordCount; 
ProgressBar1.Min:=0; 
ProgressBar1.Step:=1; 
ProgressBar1.Visible :=true; 
for i:=0 to O1.RecordCount -1 do 
begin 
s2.Close; 
S2.SQL.Clear; 
//判断SQL Server表是否存在当前的字段信息 
S2.SQL.Text:='SELECT a.name AS tanme, b.* FROM sysobjects a INNER JOIN '+ 
' syscolumns b ON a.id = b.id '+ 
' WHERE (a.xtype = ''U'') AND (a.name = '''+O1.fieldbyname('table_name')
.AsString+''''+ 
') and b.name= '''+O1.fieldbyname('COLUMN_NAME').AsString+''''+ 
' ORDER BY b.id'; 
S2.Open; 
//不存在，输出表明和字段名 
if s2.RecordCount<=0 then 
begin 
Memo1.Text:=Memo1.Text+#13+'表：'''+O1.fieldbyname('table_name').AsString+''''+ 
' 字段：'''+O1.fieldbyname('COLUMN_NAME').AsString+''' 不存在!'; 
O1.Next; 
tableN:=''; 
FieldN:=''; 
Continue; 
end; 
//是当前表，循环读取主键信息 
if (tableN='') or (tableN= O1.fieldbyname('table_name').AsString) then 
begin 
FieldN:=FieldN+'['+O1.fieldbyname('COLUMN_NAME').AsString+'],';//表明相同或初试时 
tableN:= O1.fieldbyname('table_name').AsString; 
end 
else 
begin 
with S1 do 
begin 
try 
//取SQL Server表的主键信息 
Close; 
sql.Clear; 
sql.Text:='SELECT * FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME=
'''+tableN+''''; 
Open; 
first; 
aa:=fieldbyname('constraint_name').AsString; 
//如果该主键在SQL表中已存在，删除该主键信息,重建该表主键 
if recordcount>0 then 
begin 
sql.Clear; 
SQL.Text:='ALTER TABLE '+tableN+' DROP CONSTRAINT '+aa; //删除主键 
ExecSQL; 
end; 
SQL.Clear; //COLUMN_NAME 
SQL.Text:='ALTER TABLE '+tableN+' WITH NOCHECK ADD '+ 
' CONSTRAINT [PK_'+tableN+'] PRIMARY KEY NONCLUSTERED '+ 
' ( '+ copy(FieldN,1,length(FieldN)-1)+ 
' )'; 
ExecSQL; 
FieldN:='['+O1.fieldbyname('COLUMN_NAME').AsString+'],'; 
tableN:= O1.fieldbyname('table_name').AsString; 
Except 
Memo1.Text :=Memo1.Text+'表： '+tableN+' 字段： '+FieldN+' 导入出错!'; 
exit; 
end; 
end; 
end; 
ProgressBar1.StepIt; 
Application.ProcessMessages; 
O1.Next; 
end; 
MsgBox('导入完成!'); 
finally 
Screen.Cursor :=crDefault; 
ProgressBar1.Visible :=False; 
end; 
end;