Dataset (ii) Data Reading

Method 1: Create a DataSet object

Dataset DS = new dataset ();

Dataset DS = new dataset ("datasetname ");

2. Fill dataset with a dataset

The most common method is to fill the data with dataadapter object fill ().

(1)

Dataset DS = new dataset ();

Sqldataadapter Adapt = new sqldataadapter (sqlcmd, con)

Adapt. Fill (DS, "mytest ");

(2)

Dataset DS = new dataset ();

Datatable dt = new datatable ("newtable ");

DS. Tables. Add (DT );

(3)

Dataset DS = new dataset ();

Datatable dt = Ds. Tables. Add ("newtable ");

3. Access the table, row, and column values in dataset (1): access each datatable

Access by Table Name: Ds. Tables ["mytest"] // specify the datatable object mytest (that is, access the datatable named mytest in dataset)

Access by index (index based on 0): Ds. Tables [0] // specify the first able in Dataset

(2): Access the rows in the datatable

DS. Tables ["mytest"]. Rows [N] // access row n + 1 of the mytest table (the row index starts from 0)

DS. Tables [I]. Rows [N] // access the n + 1 column of the I + 1 able in dataset (the column index starts from 0)

(3): Access an element in the datatable

DS. Tables ["mytest"]. Rows [N] [m] // access the elements in column M + 1 of row n + 1 of mytest.

DS. Tables [I]. Rows [N] [m] // access the elements in column M + 1 of row n + 1 of the I + 1 able table in Dataset

DS. Tables ["mytest"]. Rows [N] [name] // access the element of the name column in the n + 1 row of the mytest table

DS. Tables [I]. Rows [N] [name] // access the elements in the name column of the n + 1 row of the I + 1 able table in Dataset

(4): retrieve the column name in the datatable

DS. Tables ["mytest"]. Columns [N] // retrieve the n + 1 column name of the mytest table

DS. Tables [I]. Columns [N]

4. Instances

Using system;

Using system. Collections. Generic;

Using system. text;

Using system. Data. sqlclient;

Using system. Data;

Namespace sqlconnection1

{

Class Program

{

Private void sqlconnectionf (string source, string select)

{

// Create a connection

Sqlconnection con = new sqlconnection (source );

Sqldataadapter Adapt = new sqldataadapter (select, con );

Try

{

Con. open ();

Console. writeline ("connection is successful! ");

}

Catch (exception E)

{

Console. writeline ("connection error is: {0}", E. tostring ());

}

// Create a dataset

Dataset DS = new dataset ();

// Add data to Dataset

Adapt. Fill (DS, "mytest ");

// Retrieve the names of columns in the mytest table

Console. writeline ("{0,-15} {1,-10} {2,-10}", DS. Tables ["mytest"]. Columns [0],

DS. Tables ["mytest"]. Columns [1], DS. Tables ["mytest"]. Columns [2]);

// Output the sixth row of the mytest table

Datarow row1 = Ds. Tables ["mytest"]. Rows [5];

Console. writeline ("{0,-15} {1,-10} {2,-10}", row1 [0], row1 [1], row1 [2]);

// Output the value of the second column of the fifth row in the mytest table

Datarow row2 = Ds. Tables ["mytest"]. Rows [4];

Console. writeline ("{0,-25}", row2 [1]);

// The following two methods are equivalent to row2 [1] (that is, the value of the second column of the fifth line)

Console. writeline ("{0,-25}", DS. Tables ["mytest"]. Rows [4] [1]);

Console. writeline ("{0,-25}", DS. Tables ["mytest"]. Rows [4] ["Number"]);

// Output all data in Dataset

Foreach (datarow row in DS. Tables ["mytest"]. Rows)

{

Console. writeline ("{0,-15} {1,-10} {2,-10} {3}", row ["name"],

Row ["Number"], row ["low"], row ["high"]);

// Obtain the value of the third column

Console. writeline ("{0,-15}", row [3]);

}

Console. Readline ();

Con. Close ();

}

Static void main (string [] ARGs)

{

String sou = "Server = duanyf // sqlexpress;" + "Initial catalog = Master;" + "uid = sa;" + "Password = dyf123 ";

String sel = "Select name, number, low, high from DBO. spt_values ";

Program sqlcon = new program ();

Sqlcon. sqlconnectionf (SOU, Sel );

}

}

}