Dependency information and URN

I want to trunctate some tables but I need to find the right order to truncate them in because of dependencies. I have the following code:

List<Table> truncateTableList = new List<Table>();

DependencyWalker walker = new DependencyWalker(server);

for (int i = 0; i < truncateList.Length; i++)

{

truncateTableList.Add(server.Databases[_database].Tables[truncateList]);

}

DependencyTree tree = walker.DiscoverDependencies(truncateTableList.ToArray(), true);

DependencyCollection collection = walker.WalkDependencies(tree);

server.ConnectionContext.SqlExecutionModes = SqlExecutionModes.CaptureSql;

Now that I have the DependencyCollection what do I do? Looking at the nodes I see that the tree seems to be built with the parents on the top (the tables that other tables depend on) and followed by the children. I want to Truncate in reverse order from this list. Now is all I need is the names of the tables. How do I get that from the Urn?

Thank you.

Kevin

I know this is not exactly what you are trying to do, but I have a sample that walks the table dependency list so it can script the creates in the correct order, it generates a Q in the right order, I think you could take the code and tweak it for truncates. Its a lot more verbose than yours but the sample does a lot more than just this;

Code Snippet

m_UniqueTableList = new Hashtable(); //Hashtable used to check for dupes
m_TableQ = new Queue<Table>(); //Ordered list of tables
m_ServerConn = new Server(); //Server Connection

SqlSmoObject[] UnOrderedTableArr; //Array that holds the list of table objects, it could have dupes in it

...

...

//Take the unordered list and make it ordered and unique, then use the ordered list to generate the indexes, pk, fks in the right order
Scripter scripter = new Scripter(m_ServerConn);
BuildOrderedTableList(scripter.DiscoverDependencies(UnOrderedTableArr, DependencyType.Parents));

--

private void BuildOrderedTableList(DependencyTree tree)
{
DependencyTreeNode rootNode;
Table TargetTable;

// Get the first child in tree
rootNode = tree.FirstChild;

// Iterate children
while (rootNode != null)
{
// Add treeview node
if (rootNode.Urn.Type == "Table")
{

// Add child nodes to tree (this will recurse)
AddChildren(rootNode);

TargetTable = (Table)m_ServerConn.GetSmoObject(rootNode.Urn);
if (AddAndValidateTableAdd(TargetTable.Name))
{
m_TableQ.Enqueue(TargetTable);
}
}
// Skip to next child node from root
rootNode = rootNode.NextSibling;
}
}

private void AddChildren(DependencyTreeNode dependencyTreeNode)
{
DependencyTreeNode child;
Table TargetTable;

// Get first child of this node
child = dependencyTreeNode.FirstChild;

while (child != null)
{
if (child.Urn.Type == "Table")
{
// Recursively add the other nodes
AddChildren(child);

TargetTable = (Table)m_ServerConn.GetSmoObject(child.Urn);

if (AddAndValidateTableAdd(TargetTable.Name))
{
m_TableQ.Enqueue(TargetTable);
}
}
// Skip to next child node at this level
child = child.NextSibling;
}
}

//Add a table to the list, uniquely
//Use the hash table to make sure we only get one reference to each table
private bool AddAndValidateTableAdd(String TableName)
{
bool result = false;
if (!m_UniqueTableList.ContainsKey(TableName))
{
m_UniqueTableList.Add(TableName, "");
result = true;
}
return result;
}

|||

Euan Garden wrote:

I know this is not exactly what you are trying to do, but I have a sample that walks the table dependency list so it can script the creates in the correct order, it generates a Q in the right order, I think you could take the code and tweak it for truncates. Its a lot more verbose than yours but the sample does a lot more than just this;

Code Snippet

m_UniqueTableList = new Hashtable(); //Hashtable used to check for dupes
m_TableQ = new Queue<Table>(); //Ordered list of tables
m_ServerConn = new Server(); //Server Connection

SqlSmoObject[] UnOrderedTableArr; //Array that holds the list of table objects, it could have dupes in it

...

...

//Take the unordered list and make it ordered and unique, then use the ordered list to generate the indexes, pk, fks in the right order
Scripter scripter = new Scripter(m_ServerConn);
BuildOrderedTableList(scripter.DiscoverDependencies(UnOrderedTableArr, DependencyType.Parents));

--

private void BuildOrderedTableList(DependencyTree tree)
{
DependencyTreeNode rootNode;
Table TargetTable;

// Get the first child in tree
rootNode = tree.FirstChild;

// Iterate children
while (rootNode != null)
{
// Add treeview node
if (rootNode.Urn.Type == "Table")
{

// Add child nodes to tree (this will recurse)
AddChildren(rootNode);

TargetTable = (Table)m_ServerConn.GetSmoObject(rootNode.Urn);
if (AddAndValidateTableAdd(TargetTable.Name))
{
m_TableQ.Enqueue(TargetTable);
}
}
// Skip to next child node from root
rootNode = rootNode.NextSibling;
}
}

private void AddChildren(DependencyTreeNode dependencyTreeNode)
{
DependencyTreeNode child;
Table TargetTable;

// Get first child of this node
child = dependencyTreeNode.FirstChild;

while (child != null)
{
if (child.Urn.Type == "Table")
{
// Recursively add the other nodes
AddChildren(child);

TargetTable = (Table)m_ServerConn.GetSmoObject(child.Urn);

if (AddAndValidateTableAdd(TargetTable.Name))
{
m_TableQ.Enqueue(TargetTable);
}
}
// Skip to next child node at this level
child = child.NextSibling;
}
}

//Add a table to the list, uniquely
//Use the hash table to make sure we only get one reference to each table
private bool AddAndValidateTableAdd(String TableName)
{
bool result = false;
if (!m_UniqueTableList.ContainsKey(TableName))
{
m_UniqueTableList.Add(TableName, "");
result = true;
}
return result;
}

Thank you very much. One question your code starts out with an unordered table list. Where is that list obtained from?

|||I think I understand your code. I think is what I want is a little more complicated. I want to input a table and get a list of objects that depend on it. Is that possible with SMO?|||Try just passing one table object as part of the array and see what happens|||

I just get that one table returned.

My "solution" is to go through every table in the database and see if that table has a FK defined that references the given table. There is a method on each ForeignKey object call "ReferencedTable". If I compare that to the table in question I get a list of tables that have a FK reference to the table in question. For as common as this seems to me I would think a method call would solve the problem but this solution seems to work.

Thank you.

Kevin

|||If you are going through every table anyway just add them to the array and the code will work (apart from the order will be a create order)