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ADO.NET学习之SqlCommandBuilder

2017-06-12 16:02 435 查看

ADO.NET学习之SqlCommandBuilder

SqlCommandBuilder

SqlCommandBuilder automatically generates INSERT, UPDATE and DELETE sql statements based on the SELECT statement for a single table.

SqlCommandBuilder

会基于单个表的

SELECT

语句，自动生成

INSERT

、

UPDATE

和

DELETE

的

sql

语句。

使用

SqlCommandBuilder

的两个步骤：

1.设置

SqlDataAdapter

的

SelectCommand

属性

SqlDataAdapter dataAdapter = new SqlDataAdapter();
dataAdapter.SelectCommand = new SqlCommand("SELECT_Query", con);

2.创建

SqlCommandBuilder

的一个实例，并制定其

DataAdapter

属性的值

SqlCommandBuilder builder = new SqlCommandBuilder();
builder.DataAdapter = dataAdapter;

也可以一步完成，如下：

SqlCommandBuilder builder = new SqlCommandBuilder(dataAdapter);

通过例子说明

准备工作

1.创建表

tblStudents

，并添加数据

Create Table tblStudents
(
ID int identity primary key,
Name nvarchar(50),
Gender nvarchar(20),
TotalMarks int
)

Insert into tblStudents values('Mark Hastings','Male',900)
Insert into tblStudents values('Pam Nicholas','Female',760)
Insert into tblStudents values('John Stenson','Male',980)
Insert into tblStudents values('Ram Gerald','Male',990)
Insert into tblStudents values('Ron Simpson','Male',440)
Insert into tblStudents values('Able Wicht','Male',320)
Insert into tblStudents values('Steve Thompson','Male',983)
Insert into tblStudents values('James Bynes','Male',720)
Insert into tblStudents values('Mary Ward','Female',870)
Insert into tblStudents values('Nick Niron','Male',680)

2.WebForm代码

<div style="font-family: Arial">
<table border="1">
<tr>
<td>
Student ID
</td>
<td>
<asp:TextBox ID="txtStudentID" runat="server"></asp:TextBox>
<asp:Button ID="btnGetStudent" runat="server" Text="Load"
OnClick="btnGetStudent_Click" />
</td>
</tr>
<tr>
<td>
Name
</td>
<td>
<asp:TextBox ID="txtStudentName" runat="server"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Gender
</td>
<td>
<asp:DropDownList ID="ddlGender" runat="server">
<asp:ListItem Text="Select Gender" Value="-1"></asp:ListItem>
<asp:ListItem Text="Male" Value="Male"></asp:ListItem>
<asp:ListItem Text="Female" Value="Female"></asp:ListItem>
</asp:DropDownList>
</td>
</tr>
<tr>
<td>
Total Marks
</td>
<td>
<asp:TextBox ID="txtTotalMarks" runat="server"></asp:TextBox>
</td>
</tr>
<tr>
<td colspan="2">
<asp:Button ID="btnUpdate" runat="server" Text="Update"
OnClick="btnUpdate_Click" />
<asp:Label ID="lblStatus" runat="server" Font-Bold="true">
</asp:Label>
</td>
</tr>
</table>
</div>

Load

按钮根据ID查询，

Update

按钮更新数据

查询事件：

protected void btnGetStudent_Click(object sender, EventArgs e)
{
string CS = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
SqlConnection con = new SqlConnection(CS);
string sqlQuery = "select * from tblStudents where ID = " + txtStudentID.Text;
SqlDataAdapter da = new SqlDataAdapter(sqlQuery, con);
DataSet ds = new DataSet();
da.Fill(ds, "Students");
//在ViewState中保存DataSet和查询语句，将来用来SqlCommandBuilder生成命令
ViewState["SQL_QUERY"] = sqlQuery;
ViewState["DATASET"] = ds;

if (ds.Tables["Students"].Rows.Count > 0)
{
DataRow dr = ds.Tables["Students"].Rows[0];
txtStudentName.Text = dr["Name"].ToString();
txtTotalMarks.Text = dr["TotalMarks"].ToString();
ddlGender.SelectedValue = dr["Gender"].ToString();
}
else
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "No Student record with ID = " + txtStudentID.Text;
}
}

更新事件：

protected void btnUpdate_Click(object sender, EventArgs e)
{
string CS = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
SqlConnection con = new SqlConnection(CS);
SqlDataAdapter da = new SqlDataAdapter((string)ViewState["SQL_QUERY"], con);

SqlCommandBuilder builder = new SqlCommandBuilder(da);
DataSet ds = (DataSet)ViewState["DATASET"];

if (ds.Tables["Students"].Rows.Count > 0)
{
DataRow dr = ds.Tables["Students"].Rows[0];
dr["Name"] = txtStudentName.Text;
dr["Gender"] = ddlGender.SelectedValue;
dr["TotalMarks"] = txtTotalMarks.Text;
dr["Id"] = txtStudentID.Text;
}

int rowsUpdated = da.Update(ds, "Students");
if (rowsUpdated == 0)
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "No rows updated";
}
else
{
lblStatus.ForeColor = System.Drawing.Color.Green;
lblStatus.Text = rowsUpdated.ToString() + " row(s) updated";
}
}

SqlDataAdapter.Update
无效的两个原因：

1.

SqlDataAdapter

对象没有绑定

SqlCommandBuilder

对象

2.

SqlDataAdapter

的

SelectCommand

，没有返回至少一个主键或者唯一的列

如果想查看自动生成的

INSERT

UPDATE

, 和

DELETE

语句，使用

GetInsertCommand()

GetUpdateCommand()

和

GetDeleteCommand()

lblInsert.Text = builder.GetInsertCommand().CommandText;
lblUpdate.Text = builder.GetUpdateCommand().CommandText;
lblDelete.Text = builder.GetDeleteCommand().CommandText;

资料

Part 13 - What is SqlCommandBuilder

Part 14 - Sqlcommandbuilder update not working

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标签： ado.net command builder

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