Encapsulation of Database Operations

Public   Static   String Constring =   @" Server = localhost; Integrated Security = true; database = northwind " ;

1. Execute the SQL statement and return the affected number of rows.

Code
String Constring =   @" Server = localhost; Integrated Security = true; database = northwind " ;
// Execute the SQL statement and return the affected number of rows.
Public   Int Executesql ( String Strsql)
{
Sqlconnection thisconnection =   New Sqlconnection (constring );
Sqlcommand thiscommand =   New Sqlcommand (strsql, thisconnection );
Thisconnection. open ();
Int Rows = Thiscommand. executenonquery ();
Thisconnection. Close ();
Return Rows;
}

Call method: StringStrsql=@"Select * from MERs";
IntRows=Executesql (strsql );

I don't know why. After testing, the returned rows is-1. No reason is found.

2. Execute the query statement and return Dataset Code
// Execute the SQL statement and return Dataset
Public   Static Dataset query ( String Strsql)
{
Sqlconnection thisconnection =   New Sqlconnection (constring );
Dataset thisdataset =   New Dataset ();
Thisconnection. open ();
Sqldataadapter thisadapter =   New Sqldataadapter (strsql, constring );
Thisadapter. Fill (thisdataset, " DS " );
Thisconnection. Close ();
Return Thisdataset;
}

Call method:

String Strsql =   @" Select * from MERs " ;
Dataset DS = Utility. Query (strsql );

3. Execute a statement to calculate the query result and return the query result (object) Code
// Execute a calculation Query Result Statement and return the query result (object)
Public   Static   Object Getsingle ( String Strsql)
{
Sqlconnection thisconnection =   New Sqlconnection (constring );
Sqlcommand thiscommand =   New Sqlcommand (strsql, thisconnection );
Thisconnection. open ();
Object OBJ = Thiscommand. executescalar ();
If (Object. Equals (OBJ, Null )) | (Object. Equals (OBJ, system. dbnull. Value )))
{
Return   Null ;
}
Else
{
Return OBJ;
}
}

Call method:

String Strsql =   @" Select * from MERs " ;
String Num = Utility. getsingle (strsql). tostring ();

5. Execute SQL statements with parameters and return the number of affected records
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