轻松搞定数据访问层[续1]

' clsSQLBuilder

‘ By YuHonglai

‘ www.hahaIT.com

‘ hahasoft@msn.com

' Note:提供重载方法以指明表名称，默认情况下，是传入参数 o 的类型＋"tbl_",此时类名称必须是 clsXXX 的形式.

' 如：

' dim Rooms as new clsRooms

' SQLBuilder.Add(Rooms)

' 此时程序将把 clsRooms 转换成 tbl_Rooms,以操作数据库表 tbl_Rooms

' 如果类名称和数据库表名称不具有上述对应关系，请使用 Add(o,"TableName")形式的方法，以显示指定要操作的数据库表的名称

Public Class SQLBuilder

' 当要生成的SQL语句的 where 条件语句很复杂时，用该常量作为 Select 方法中 FindCondition(HashTable)

' Key,例如：要生成 where Birth<'2000-4-4' and Birth>'1980-1-1' 的复杂条件时，用以下方法:

' Dim h as new HashTable

' h.Add(ComplexSQL,"_Birth<'2000-4-4' and _Birth>'1980-1-1'")

' 注意，Birth是实体类的属性名称，前面必须有一个下划线 "_"

' 处理时，程序将用实际数据库字段名称代替相应的 _Birth

Public Const ComplexSQL As String = "@ComplexSQL"

' 根具实体类生成相应的 Insert ...SQL 语句

' 如果与数据库表名称对应的属性时关键字段而且是自动增加值时(在DB.XML文件中seed的值为 1 )

' 那么该属相将忽略,不会出现在返回的 Insert... SQL语句中

Public Overloads Shared Function Add(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return Add(o, typeString)

End Function

Public Overloads Shared Function Add(ByVal o As Object, ByVal TableName As String) As String

Try

Dim outSQL As String

Dim tmpString As String

outSQL = "insert into [" & TableName & "]("

tmpString = ""

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("seed") & "" = "0" Then

outSQL = outSQL & row.Item("dbname") & ","

tmpString = tmpString & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & ","

End If

outSQL = outSQL.Substring(0, outSQL.Length - 1)

tmpString = tmpString.Substring(0, tmpString.Length - 1)

outSQL = outSQL & ") values (" & tmpString & ")"

For Each row In dsDB.Tables(TableName).Rows

If row.Item("seed") & "" <> "1" Then

' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

If tmpString = "True" Then

tmpString = "1"

ElseIf tmpString = "False" Then

tmpString = "0"

End If

outSQL = outSQL.Replace("@" & row.Item("dbname"), tmpString)

End If

Return outSQL.Trim

Catch ex As Exception

Throw ex

End Try

End Function

' 如 Add 方法，关键字段不会更新

' 而且关键字段会作为 update....where .... 的 where 的条件出现

Public Overloads Shared Function Update(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return Update(o, typeString)

End Function

Public Overloads Shared Function Update(ByVal o As Object, ByVal TableName As String) As String

Try

Dim outString As String = ""

Dim tmpString As String

outString = "update [" & TableName & "] set "

tmpString = ""

Dim whereString As String = ""

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") & "" = "1" Then

whereString = whereString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & " and "

Else

tmpString = tmpString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & ","

End If

If whereString.Trim = "" Then

Throw New Exception("必须指定一个以上的主键!")

End If

tmpString = tmpString.Substring(0, tmpString.Length - 1)

whereString = whereString.Substring(0, whereString.Length - 4)

outString = outString & tmpString & " where " & whereString

For Each row In dsDB.Tables(TableName).Rows

' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

If tmpString = "True" Then

tmpString = "1"

ElseIf tmpString = "False" Then

tmpString = "0"

End If

outString = outString.Replace("@" & row.Item("dbname"), tmpString)

Return outString.Trim

Catch ex As Exception

Throw ex

End Try

End Function

' 更具对象的关键属性(与数据库表的关键字段对应)删除指定的记录

' 对象的其他属性将被忽略

Public Overloads Shared Function Delete(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return Delete(o, typeString)

End Function

Public Overloads Shared Function Delete(ByVal o As Object, ByVal TableName As String) As String

Try

Dim outString As String = ""

Dim tmpString As String

outString = "delete from [" & TableName & "] where "

Dim whereString As String = ""

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") & "" = "1" Then

whereString = whereString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & " and "

End If

If whereString.Trim = "" Then

Throw New Exception("必须指定一个以上的主键!")

End If

whereString = whereString.Substring(0, whereString.Length - 4)

outString = outString & tmpString & whereString

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") & "" = "1" Then

' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

outString = outString.Replace("@" & row.Item("dbname"), tmpString)

End If

Return outString.Trim

Catch ex As Exception

Throw ex

End Try

End Function

' 更具对象的关键属性(与数据库表的关键字段对应)判断该对象是否存在于数据库中

' 对象的其他属性将被忽略

Public Overloads Shared Function Exists(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return Exists(o, typeString)

End Function

Public Overloads Shared Function Exists(ByVal o As Object, ByVal TableName As String) As String

Try

Dim outString As String

outString = "select count(*) from [" & TableName & "] where "

Dim tmpString As String

Dim whereString As String = ""

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") & "" = "1" Then

whereString = whereString & row.Item("dbname") & "=" & getS(row.Item("type")) & "@" & row.Item("dbname") & getS(row.Item("type")) & " and "

End If

If whereString.Trim = "" Then

Throw New Exception("必须指定一个以上的主键!")

End If

whereString = whereString.Substring(0, whereString.Length - 4)

outString = outString & tmpString & whereString

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") & "" = "1" Then

' tmpString = o.GetType.InvokeMember(row.Item("name"), Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

tmpString = CallByName(o, CType(row.Item("name"), String).Trim, CallType.Get) & ""

outString = outString.Replace("@" & row.Item("dbname"), tmpString)

End If

Return outString.Trim

Catch ex As Exception

Throw ex

End Try

End Function

' 生成 First SQL语句

Public Overloads Shared Function First(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return First(typeString)

End Function

Public Overloads Shared Function First(ByVal TableName As String) As String

Dim MoudleSQL As String

MoudleSQL = "select * from [%TableName%] where [%key%] in(select Min([%key%]) from [%TableName%])"

Dim key As String

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") = "1" Then

key = CType(row.Item("dbname"), String).Trim

Exit For

End If

MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

MoudleSQL = MoudleSQL.Replace("%key%", key)

Return MoudleSQL

End Function

Public Overloads Shared Function Last(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return Last(typeString)

End Function

Public Overloads Shared Function Last(ByVal TableName As String) As String

Dim MoudleSQL As String

MoudleSQL = "select * from [%TableName%] where [%key%] in(select Max([%key%]) from [%TableName%])"

Dim key As String

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") = "1" Then

key = CType(row.Item("dbname"), String).Trim

Exit For

End If

MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

MoudleSQL = MoudleSQL.Replace("%key%", key)

Return MoudleSQL

End Function

Public Overloads Shared Function Previous(ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return Previous(o, typeString)

End Function

Public Overloads Shared Function Previous(ByVal o As Object, ByVal TableName As String) As String

Dim MoudleSQL As String

MoudleSQL = "select * from [%TableName%] where [%key%] in(select Max([%key%]) from [%TableName%] where [%key%]<%keyValue%)"

Dim key As String

Dim propertyName As String

Dim propertyValue As String

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") = "1" Then

key = CType(row.Item("dbname"), String).Trim

propertyName = CType(row.Item("name"), String).Trim

Exit For

End If

' propertyValue = o.GetType.InvokeMember(propertyName, Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

propertyValue = CallByName(o, propertyName, CallType.Get) & ""

MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

MoudleSQL = MoudleSQL.Replace("%key%", key)

MoudleSQL = MoudleSQL.Replace("%keyValue%", propertyValue)

Return MoudleSQL

End Function

Public Overloads Shared Function [Next](ByVal o As Object) As String

Dim typeString As String = o.GetType.ToString

Dim i As Int16

i = typeString.IndexOf("cls") + 3

typeString = "tbl_" & typeString.Substring(i, typeString.Length - i)

Return [Next](o, typeString)

End Function

Public Overloads Shared Function [Next](ByVal o As Object, ByVal TableName As String) As String

Dim MoudleSQL As String

MoudleSQL = "select * from [%TableName%] where [%key%] in(select Min([%key%]) from [%TableName%] where [%key%]>%keyValue%)"

Dim key As String

Dim propertyName As String

Dim propertyValue As String

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim row As Data.DataRow

For Each row In dsDB.Tables(TableName).Rows

If row.Item("key") = "1" Then

key = CType(row.Item("dbname"), String).Trim

propertyName = CType(row.Item("name"), String).Trim

Exit For

End If

' propertyValue = o.GetType.InvokeMember(propertyName, Reflection.BindingFlags.GetField Or Reflection.BindingFlags.GetProperty, Nothing, o, New Object() {}) & ""

propertyValue = CallByName(o, propertyName, CallType.Get) & ""

MoudleSQL = MoudleSQL.Replace("%TableName%", TableName)

MoudleSQL = MoudleSQL.Replace("%key%", key)

MoudleSQL = MoudleSQL.Replace("%keyValue%", propertyValue)

Return MoudleSQL

End Function

' 见 public const ComplexSQL 的说明

Public Shared Function [Select](ByVal FindCondition As Hashtable, ByVal TableName As String) As String

Dim outSQL As String

If FindCondition.Contains(ComplexSQL) Then ' 处理复杂类型的 Where 从句

outSQL = "select * from [" & TableName & "] where " & FindCondition(ComplexSQL)

Dim row As Data.DataRow

Dim dsDB As New DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

For Each row In dsDB.Tables(TableName).Rows

outSQL = outSQL.Replace("_" & CType(row.Item("name"), String).Trim, "[" & CType(row.Item("dbname"), String).Trim & "]")

Else

outSQL = "select * from [" & TableName & "] where "

Dim whereString As String = ""

Dim eachKey As Object

For Each eachKey In FindCondition.Keys

whereString = whereString & CType(eachKey, String) & "=" & getS(getTypeByName(TableName, CType(eachKey, String))) & FindCondition(eachKey) & getS(getTypeByName(TableName, CType(eachKey, String))) & " and "

If whereString.Length = 0 Then

whereString = "0=0"

Else

whereString = whereString.Substring(0, whereString.Length - 5)

End If

outSQL = outSQL & whereString

End If

Return outSQL

End Function

' 返回指定的字段(数据库表字段的名称)的数据类型名称(VB数据类型)

Private Shared Function getTypeByName(ByVal TableName As String, ByVal n As String) As String

Dim outStr As String

Dim dsDB As New Data.DataSet

dsDB.ReadXml(clsPersistant.DBConfigPath)

Dim eachRow As DataRow

For Each eachRow In dsDB.Tables(TableName).Rows

If CType(eachRow.Item("dbname"), String).Trim.ToLower = n.Trim.ToLower Then

outStr = CType(eachRow.Item("type"), String).Trim.ToLower

Exit For

End If

Return outStr

End Function

' 根具数据类型名称，返回空或' SQL语句中数字和字符型是否被‘括起来

Private Shared Function getS(ByVal t As String) As String

Dim outString As String

t = t.ToLower.Trim

If t = "single" Or t = "int16" Or t = "int32" Or t = "int64" Or t = "double" Or t = "byte" Then

outString = ""

Return outString

ElseIf t = "date" Or t = "string" Then

outString = "'"

Return outString

End If

End Function

End Class