在與數據庫進行交互時,我們使用到了一個CodeSmith自帶的組件SchemaExplorer,利用這個組件我們可以訪問數據庫的數據表、存儲過程、視圖等,並可以得到相應的數據類型、標識列、列的(字段)名稱等信息。
下面這個例子是教我們如何生成一個存儲過程,雖然網上有很多一樣的例子,但是我是從CodeSmith中的英文幫助中自己翻譯出來的:)
使用的是SQL Server 2000自帶的Northwind數據庫,生成一個關於Orders訂單表的更新存儲過程。
第一步還是指明模板使用的語言和生成的目標語言。
<%@ CodeTemplate Language="C#" TargetLanguage="T-SQL" Description="Generates a update stored procedure." %>
第二步就是我們要加載使用訪問數據庫的組件SchemaExplorer,並聲明其使用的命名空間。
<%@ Assembly Name="SchemaExplorer" %>
<%@ Import Namespace="SchemaExplorer" %>
<%@ Import Namespace="SchemaExplorer" %>
因爲是針對表去生成存儲過程,則首先要定義一個存儲表名稱使用的變量,然後指明這個變量類型爲數據庫中的表,這樣我們可以通過這個數據表類型的變量得到相應的表的信息。
<%@ Property Name="SourceTable" Type="SchemaExplorer.TableSchema" Category="Context" Description="Table that the stored procedures should be based on." %>
如果想訪問視圖的話,則將變量類型Type中的SchemaExplorer.TableSchema修改爲SchemaExplorer.ViewSchema即可。
得到表名的方法
CREATEPROCEDURE dbo.Update<%= SourceTable.Name %>
下面利用循環語句遍歷表的各個列,拼出存儲過程需要傳遞的參數。
<%for (int i =0; i < SourceTable.Columns.Count; i++) { %>
<%= GetSqlParameterStatement(SourceTable.Columns[i]) %><%if (i < SourceTable.Columns.Count -1) { %>,<% } %>
<% } %>
<%= GetSqlParameterStatement(SourceTable.Columns[i]) %><%if (i < SourceTable.Columns.Count -1) { %>,<% } %>
<% } %>
調用的GetSqlParameterStatement方法是用來生成參數的字符串,例如生成“@CustomerID nchar(5)”,後邊緊跟的if判斷是用來生成參數之間相隔使用的逗號的。
生成參數字符串的方法,參數爲SchemaExplorer.ColumnSchema列類型
1<script runat="template">
2public string GetSqlParameterStatement(ColumnSchema column)
3{
4 string param ="@"+ column.Name +""+ column.NativeType;
5
6switch (column.DataType)
7 {
8case DbType.Decimal:
9 {
10 param +="("+ column.Precision +", "+ column.Scale +")";
11break;
12 }
13default:
14 {
15if (column.Size >0)
16 {
17 param +="("+ column.Size +")";
18 }
19break;
20 }
21 }
22
23return param;
24}
25</script>
2public string GetSqlParameterStatement(ColumnSchema column)
3{
4 string param ="@"+ column.Name +""+ column.NativeType;
5
6switch (column.DataType)
7 {
8case DbType.Decimal:
9 {
10 param +="("+ column.Precision +", "+ column.Scale +")";
11break;
12 }
13default:
14 {
15if (column.Size >0)
16 {
17 param +="("+ column.Size +")";
18 }
19break;
20 }
21 }
22
23return param;
24}
25</script>
下面來生成需要更新的字段,更新時僅能更新非主鍵字段的值,在SchemaExplorer中支持這種區別,使用SourceTable.NonPrimaryKeyColumns即可得到非主鍵字段的集合。
1UPDATE[<%= SourceTable.Name %>]SET
2<%for (int i =0; i < SourceTable.NonPrimaryKeyColumns.Count; i++) { %>
3[<%= SourceTable.NonPrimaryKeyColumns[i].Name %>] = @<%= SourceTable.NonPrimaryKeyColumns[i].Name %><%if (i < SourceTable.NonPrimaryKeyColumns.Count-1) { %>,<% } %>
4<% } %>
2<%for (int i =0; i < SourceTable.NonPrimaryKeyColumns.Count; i++) { %>
3[<%= SourceTable.NonPrimaryKeyColumns[i].Name %>] = @<%= SourceTable.NonPrimaryKeyColumns[i].Name %><%if (i < SourceTable.NonPrimaryKeyColumns.Count-1) { %>,<% } %>
4<% } %>
然後再使用SourceTable.PrimaryKey.MemberColumns得到數據表中的主鍵集合,生成更新條件
1WHERE
2<%for (int i =0; i < SourceTable.PrimaryKey.MemberColumns.Count; i++) { %>
3<%if (i >0) { %>AND<% } %>
4[<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>] = @<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>
5<% } %>
2<%for (int i =0; i < SourceTable.PrimaryKey.MemberColumns.Count; i++) { %>
3<%if (i >0) { %>AND<% } %>
4[<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>] = @<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>
5<% } %>
以下爲整體的代碼結構
1<%@ CodeTemplate Language="C#" TargetLanguage="T-SQL"
2 Description="Generates a update stored procedure." %>
3
4<%@ Property Name="SourceTable" Type="SchemaExplorer.TableSchema"
5 Category="Context"
6 Description="Table that the stored procedures should be based on." %>
7
8<%@ Assembly Name="SchemaExplorer" %>
9
10<%@ Import Namespace="SchemaExplorer" %>
11
12<script runat="template">
13public string GetSqlParameterStatement(ColumnSchema column)
14{
15 string param = "@" + column.Name + " " + column.NativeType;
16
17 switch (column.DataType)
18 {
19 case DbType.Decimal:
20 {
21 param += "(" + column.Precision + ", " + column.Scale + ")";
22 break;
23 }
24 default:
25 {
26 if (column.Size > 0)
27 {
28 param += "(" + column.Size + ")";
29 }
30 break;
31 }
32 }
33
34 return param;
35}
36</script>
37
38-----------------------------------------------------------------
39-- Date Created: <%= DateTime.Now.ToLongDateString() %>
40-- Created By: Generated by CodeSmith
41-----------------------------------------------------------------
42
43CREATE PROCEDURE dbo.Update<%= SourceTable.Name %>
44<% for (int i = 0; i < SourceTable.Columns.Count; i++) { %>
45<%= GetSqlParameterStatement(SourceTable.Columns[i]) %><% if (i < SourceTable.Columns.Count - 1) { %>,<% } %>
46<% } %>
47AS
48
49UPDATE [<%= SourceTable.Name %>] SET
50<% for (int i = 0; i < SourceTable.NonPrimaryKeyColumns.Count; i++) { %>
51 [<%= SourceTable.NonPrimaryKeyColumns[i].Name %>] = @<%= SourceTable.NonPrimaryKeyColumns[i].Name %><% if (i < SourceTable.NonPrimaryKeyColumns.Count - 1) { %>,<% } %>
52<% } %>
53WHERE
54<% for (int i = 0; i < SourceTable.PrimaryKey.MemberColumns.Count; i++) { %>
55<% if (i > 0) { %>AND <% } %>
56 [<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>] = @<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>
57<% } %>
58http://www.cnblogs.com/Bear-Study-Hard/archive/2005/12/19/300142.html
2 Description="Generates a update stored procedure." %>
3
4<%@ Property Name="SourceTable" Type="SchemaExplorer.TableSchema"
5 Category="Context"
6 Description="Table that the stored procedures should be based on." %>
7
8<%@ Assembly Name="SchemaExplorer" %>
9
10<%@ Import Namespace="SchemaExplorer" %>
11
12<script runat="template">
13public string GetSqlParameterStatement(ColumnSchema column)
14{
15 string param = "@" + column.Name + " " + column.NativeType;
16
17 switch (column.DataType)
18 {
19 case DbType.Decimal:
20 {
21 param += "(" + column.Precision + ", " + column.Scale + ")";
22 break;
23 }
24 default:
25 {
26 if (column.Size > 0)
27 {
28 param += "(" + column.Size + ")";
29 }
30 break;
31 }
32 }
33
34 return param;
35}
36</script>
37
38-----------------------------------------------------------------
39-- Date Created: <%= DateTime.Now.ToLongDateString() %>
40-- Created By: Generated by CodeSmith
41-----------------------------------------------------------------
42
43CREATE PROCEDURE dbo.Update<%= SourceTable.Name %>
44<% for (int i = 0; i < SourceTable.Columns.Count; i++) { %>
45<%= GetSqlParameterStatement(SourceTable.Columns[i]) %><% if (i < SourceTable.Columns.Count - 1) { %>,<% } %>
46<% } %>
47AS
48
49UPDATE [<%= SourceTable.Name %>] SET
50<% for (int i = 0; i < SourceTable.NonPrimaryKeyColumns.Count; i++) { %>
51 [<%= SourceTable.NonPrimaryKeyColumns[i].Name %>] = @<%= SourceTable.NonPrimaryKeyColumns[i].Name %><% if (i < SourceTable.NonPrimaryKeyColumns.Count - 1) { %>,<% } %>
52<% } %>
53WHERE
54<% for (int i = 0; i < SourceTable.PrimaryKey.MemberColumns.Count; i++) { %>
55<% if (i > 0) { %>AND <% } %>
56 [<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>] = @<%= SourceTable.PrimaryKey.MemberColumns[i].Name %>
57<% } %>
58http://www.cnblogs.com/Bear-Study-Hard/archive/2005/12/19/300142.html