private static IExprExec?WhenMatched(ExprMerge merge, TempTableBase tempTable)
{
IExprExec?e = null;
if (merge.WhenMatched != null)
{
if (merge.WhenMatched is ExprMergeMatchedUpdate update)
{
e = SqQueryBuilder
.Update(merge.TargetTable)
.Set(update.Set)
.From(merge.TargetTable)
.InnerJoin(tempTable, merge.On)
.Where(update.And);
}
else if (merge.WhenMatched is ExprMergeMatchedDelete delete)
{
ExprBoolean filter = SqQueryBuilder.Exists(SqQueryBuilder.SelectOne()
.From(tempTable)
.Where(merge.On));
if (delete.And != null)
{
filter = filter & delete.And;
}
e = SqQueryBuilder.Delete(merge.TargetTable).From(merge.TargetTable).Where(filter);
}
else
{
throw new SqExpressException($"Unknown type: '{merge.WhenMatched.GetType().Name}'");
}
}
return(e);
}
private static IExprExec?WhenNotMatchedByTarget(ExprMerge merge, TempTableBase tempTable, ExtractKeysResult keys)
{
IExprExec?e = null;
if (merge.WhenNotMatchedByTarget != null)
{
if (merge.WhenNotMatchedByTarget is ExprExprMergeNotMatchedInsert insert)
{
var filter = !SqQueryBuilder.Exists(SqQueryBuilder
.SelectOne()
.From(merge.TargetTable)
.Where(merge.On));
if (insert.And != null)
{
filter = filter & insert.And;
}
e = SqQueryBuilder.InsertInto(merge.TargetTable, insert.Columns)
.From(SqQueryBuilder.Select(insert.Values.SelectToReadOnlyList(i =>
i is ExprValue v
? v
: throw new SqExpressException("DEFAULT value cannot be used in MERGE polyfill")))
.From(tempTable)
.Where(filter));
}
else if (merge.WhenNotMatchedByTarget is ExprExprMergeNotMatchedInsertDefault insertDefault)
{
var filter = !SqQueryBuilder.Exists(SqQueryBuilder
.SelectOne()
.From(merge.TargetTable)
.Where(merge.On));
if (insertDefault.And != null)
{
filter = filter & insertDefault.And;
}
e = SqQueryBuilder.InsertInto(merge.TargetTable, keys.TargetKeys)
.From(SqQueryBuilder.Select(keys.SourceKeys)
.From(tempTable)
.Where(filter));
}
else
{
throw new SqExpressException($"Unknown type: '{merge.WhenNotMatchedByTarget.GetType().Name}'");
}
}
return(e);
}
public static ExprList FromDerivedTableValuesInsert(ExprDerivedTableValues derivedTableValues, IReadOnlyList <ExprColumnName>?keys, out TempTableBase tempTable, Alias alias = default, string?name = null)
{
tempTable = FromDerivedTableValues(derivedTableValues, keys, alias, name);
var insertData = derivedTableValues.Values.Items.SelectToReadOnlyList(r => new ExprInsertValueRow(r.Items));
var insert = SqQueryBuilder.InsertInto(tempTable, derivedTableValues.Columns).Values(new ExprInsertValues(insertData));
return(new ExprList(new IExprExec[] { new ExprStatement(tempTable.Script.Create()), insert }));
}
