protected virtual void GenerateDependentTableCopy(ReferenceGraph.Vertex vertex)
{
var table = vertex.Table;
var dependentReferences = vertex.DependentReferences
// Check constraints can lead to nullable dependent reference columns. However, rows needs to be dependent
// on something copied, so if there's only one dependency we might as well inner join on it regardless.
.Select(r => new { r.ParentColumn, r.ReferencedTable, UseLeftJoin = r.ParentColumn.IsNullable && vertex.DependentReferences.Count > 1 })
.ToReadOnlyList();
var selectColumnNames = dependentReferences
.Select((r, i) => $"j{i}.InsertedID j{i}InsertedID");
// If necessary (it usually isn't), make sure something in the row is dependent on something copied. Faster to
// or together where-ins than it is to coalesce on all left joined columns and perform a not null check.
string fromClause = dependentReferences.All(r => r.UseLeftJoin)
? $@"FROM (
SELECT *
FROM [{table.Schema}].[{table.Name}]
WHERE {string.Join($"{Separators.Nlw16}OR ", dependentReferences.Select(r => $"[{r.ParentColumn.Name}] IN (SELECT ExistingID FROM {TableVariableNames[r.ReferencedTable]})"))}
) AS copy"
: $@"FROM [{table.Schema.Name}].[{table.Name}] copy";
var joinClauses = dependentReferences
.Select((r, i) => $"{(r.UseLeftJoin ? "LEFT " : "")}JOIN {TableVariableNames[r.ReferencedTable]} j{i}{Separators.Nlw12}ON copy.[{r.ParentColumn.Name}] = j{i}.ExistingID");
var dependentInsertColumnNames = dependentReferences
.Select(r => $"[{r.ParentColumn.Name}]");
var dependentInsertColumnValues = dependentReferences
// A potential left join should leave InsertedID null only if the original value was null, since this is a root copy.
.Select((r, i) => $"j{i}InsertedID");
var nonDependentInsertColumns = table.Columns
.Where(c => c.IsCopyable)
.Where(c => !ExcludedColumns.Contains(c))
.Where(c => !dependentReferences.Select(r => r.ParentColumn).Contains(c));
var nonDependentInsertColumnNames = nonDependentInsertColumns
.Select(c => $"[{c.Name}]");
var nonDependentInsertColumnValues = nonDependentInsertColumns
.Select(c => UpdateParameterNames.ContainsKey(c) ? UpdateParameterNames[c] : $"Source.[{c.Name}]");
ProcedureBody.AppendLine($@"
MERGE INTO [{table.Schema.Name}].[{table.Name}] AS Target
USING (
SELECT
copy.*,
{string.Join(Separators.Cnlw12, selectColumnNames)}
{fromClause}
{string.Join(Separators.Nlw8, joinClauses)}
) AS Source
ON 1 = 0
WHEN NOT MATCHED BY TARGET THEN
INSERT (
{string.Join(Separators.Cnlw8, dependentInsertColumnNames.Concat(nonDependentInsertColumnNames))})
VALUES (
{string.Join(Separators.Cnlw8, dependentInsertColumnValues.Concat(nonDependentInsertColumnValues))}){GenerateOutputClause(table)}");
}
protected override void GenerateDependentTableCopy(ReferenceGraph.Vertex vertex)
{
var table = vertex.Table;
var dependentReferences = vertex.DependentReferences;
// Rows needs to be dependent on something copied, so if there's only one dependency we might as well inner join on it.
bool useLeftJoin = dependentReferences.Count > 1;
var selectColumnNames = dependentReferences
.Select((r, i) => $"j{i}.InsertedID j{i}InsertedID");
// If necessary (it often is), make sure something in the row is dependent on something copied. Faster to
// or together where-ins than it is to coalesce on all left joined columns and perform a not null check.
string fromClause = useLeftJoin
? $@"FROM (
SELECT *
FROM [{table.Schema}].[{table.Name}]
WHERE {string.Join($"{Separators.Nlw16} OR ", dependentReferences.Select(r => $"[{r.ParentColumn.Name}] IN (SELECT ExistingID FROM {TableVariableNames[r.ReferencedTable]})"))}
) AS copy"
: $@"FROM [{table.Schema.Name}].[{table.Name}] copy";
var joinClauses = dependentReferences
.Select((r, i) => new { r.ParentColumn, r.ReferencedTable, JoinString = $"{(useLeftJoin ? "LEFT " : "")}JOIN" })
.Select((r, i) => $"{r.JoinString} {TableVariableNames[r.ReferencedTable]} j{i}{Separators.Nlw12}ON copy.[{r.ParentColumn.Name}] = j{i}.ExistingID");
var dependentInsertColumnNames = dependentReferences
.Select(r => $"[{r.ParentColumn.Name}]");
var dependentInsertColumnValues = dependentReferences
.Select((r, i) => useLeftJoin ? $"COALESCE(j{i}InsertedID, [{r.ParentColumn.Name}])" : $"j{i}InsertedID");
var nonDependentInsertColumns = table.Columns
.Where(c => c.IsCopyable)
.Where(c => !ExcludedColumns.Contains(c))
.Where(c => !dependentReferences.Select(r => r.ParentColumn).Contains(c));
var nonDependentInsertColumnNames = nonDependentInsertColumns
.Select(c => $"[{c.Name}]");
var nonDependentInsertColumnValues = nonDependentInsertColumns
.Select(c => UpdateParameterNames.ContainsKey(c) ? UpdateParameterNames[c] : $"Source.[{c.Name}]");
ProcedureBody.AppendLine($@"
MERGE INTO [{table.Schema.Name}].[{table.Name}] AS Target
USING (
SELECT
copy.*,
{string.Join(Separators.Cnlw12, selectColumnNames)}
{fromClause}
{string.Join(Separators.Nlw8, joinClauses)}
) AS Source
ON 1 = 0
WHEN NOT MATCHED BY TARGET THEN
INSERT (
{string.Join(Separators.Cnlw8, dependentInsertColumnNames.Concat(nonDependentInsertColumnNames))})
VALUES (
{string.Join(Separators.Cnlw8, dependentInsertColumnValues.Concat(nonDependentInsertColumnValues))}){GenerateOutputClause(table)}");
}
protected virtual void GenerateNonDependentReferenceUpdates(ReferenceGraph.Vertex vertex)
{
var table = vertex.Table;
var nonDependentReferences = vertex.NonDependentReferences;
// Since this is a root copy, all non-null original values should have corresponding InsertedIDs. It's not necessary
// to worry about what to do with references (between tables in the subgraph of the database discovered from whatever the
// root table is) to non-copied data, because there shouldn't be any such references. So if there's only one dependency,
// inner join, otherwise left join WITH a coalesce--because triggers could've already updated these references underneath us!
// Added side benefit: coalescing here makes this code exactly what we want in the deep copy case.
bool useLeftJoin = nonDependentReferences.Count > 1;
var setStatements = useLeftJoin ? nonDependentReferences
.Select((r, i) => $"copy.[{r.ParentColumn.Name}] = COALESCE(j{i}.InsertedID, copy.[{r.ParentColumn.Name}])") : nonDependentReferences
.Select((r, i) => $"copy.[{r.ParentColumn.Name}] = j{i}.InsertedID");
var joinClauses = nonDependentReferences
.Select((r, i) => $"{(useLeftJoin ? "LEFT " : "")}JOIN {TableVariableNames[r.ReferencedTable]} j{i}{Separators.Nlw8}ON copy.[{r.ParentColumn.Name}] = j{i}.ExistingID");
ProcedureBody.AppendLine($@"
UPDATE copy
SET
{string.Join(Separators.Cnlw8, setStatements)}
FROM [{table.Schema.Name}].[{table.Name}] copy
{string.Join(Separators.Nlw4, joinClauses)}
WHERE copy.[{table.PrimaryKey.Column.Name}] IN (SELECT InsertedID FROM {TableVariableNames[table]});");
}
