71 lines
3.6 KiB
VB.net
71 lines
3.6 KiB
VB.net
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Imports System.Collections.Generic
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Imports System.Text
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Namespace Database.Base
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Public Module TriggerBuilder
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Public Function GetForeignKeyTriggers(ByVal dt As TableSchema) As IList(Of TriggerSchema)
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Dim result As IList(Of TriggerSchema) = New List(Of TriggerSchema)()
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For Each fks As ForeignKeySchema In dt.ForeignKeys
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result.Add(GenerateInsertTrigger(fks))
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result.Add(GenerateUpdateTrigger(fks))
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result.Add(GenerateDeleteTrigger(fks))
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Next
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Return result
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End Function
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Private Function MakeTriggerName(ByVal fks As ForeignKeySchema, ByVal prefix As String) As String
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Return prefix & "_" & fks.TableName & "_" & fks.ColumnName & "_" & fks.ForeignTableName & "_" & fks.ForeignColumnName
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End Function
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Public Function GenerateInsertTrigger(ByVal fks As ForeignKeySchema) As TriggerSchema
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Dim trigger As TriggerSchema = New TriggerSchema()
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trigger.Name = MakeTriggerName(fks, "fki")
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trigger.Type = TriggerType.Before
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trigger.Event = TriggerEvent.Insert
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trigger.Table = fks.TableName
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Dim nullString As String = ""
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If fks.IsNullable Then
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nullString = " NEW." & fks.ColumnName & " IS NOT NULL AND"
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End If
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trigger.Body = "SELECT RAISE(ROLLBACK, 'insert on table " & fks.TableName & " violates foreign key constraint " & trigger.Name & "')" & " WHERE" & nullString & " (SELECT " & fks.ForeignColumnName & " FROM " & fks.ForeignTableName & " WHERE " & fks.ForeignColumnName & " = NEW." & fks.ColumnName & ") IS NULL; "
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Return trigger
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End Function
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Public Function GenerateUpdateTrigger(ByVal fks As ForeignKeySchema) As TriggerSchema
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Dim trigger As TriggerSchema = New TriggerSchema()
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trigger.Name = MakeTriggerName(fks, "fku")
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trigger.Type = TriggerType.Before
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trigger.Event = TriggerEvent.Update
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trigger.Table = fks.TableName
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Dim triggerName As String = trigger.Name
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Dim nullString As String = ""
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If fks.IsNullable Then
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nullString = " NEW." & fks.ColumnName & " IS NOT NULL AND"
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End If
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trigger.Body = "SELECT RAISE(ROLLBACK, 'update on table " & fks.TableName & " violates foreign key constraint " & triggerName & "')" & " WHERE" & nullString & " (SELECT " & fks.ForeignColumnName & " FROM " & fks.ForeignTableName & " WHERE " & fks.ForeignColumnName & " = NEW." & fks.ColumnName & ") IS NULL; "
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Return trigger
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End Function
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Public Function GenerateDeleteTrigger(ByVal fks As ForeignKeySchema) As TriggerSchema
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Dim trigger As TriggerSchema = New TriggerSchema()
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trigger.Name = MakeTriggerName(fks, "fkd")
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trigger.Type = TriggerType.Before
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trigger.Event = TriggerEvent.Delete
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trigger.Table = fks.ForeignTableName
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Dim triggerName as String = trigger.Name
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If Not fks.CascadeOnDelete Then
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trigger.Body = "SELECT RAISE(ROLLBACK, 'delete on table " & fks.ForeignTableName & " violates foreign key constraint " & triggerName & "')" & " WHERE (SELECT " & fks.ColumnName & " FROM " & fks.TableName & " WHERE " & fks.ColumnName & " = OLD." & fks.ForeignColumnName & ") IS NOT NULL; "
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Else
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trigger.Body = "DELETE FROM [" & fks.TableName & "] WHERE " & fks.ColumnName & " = OLD." & fks.ForeignColumnName & "; "
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End If
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Return trigger
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End Function
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End Module
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End NameSpace
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