/// <summary>
/// This is a helper method that generates an if statement that checks the batches executed
/// table to see if the current batch has been executed. The if statement will look like this
///
/// if not exists(select 1 from [tempdb].[dbo].[$(CompletedBatches)]
/// where BatchId = batchId)
/// begin
/// end
/// </summary>
/// <param name="batchId"></param>
/// <returns></returns>
private static IfStatement CreateIfNotExecutedStatement(int batchId)
{
// Create the exists/select statement
ExistsPredicate existsExp = new ExistsPredicate();
ScalarSubquery subQuery = new ScalarSubquery();
existsExp.Subquery = subQuery;
subQuery.QueryExpression = new QuerySpecification
{
SelectElements =
{
new SelectScalarExpression {
Expression = new IntegerLiteral{
Value = "1"
}
}
},
FromClause = new FromClause
{
TableReferences =
{
new NamedTableReference()
{
SchemaObject = CreateCompletedBatchesName()
}
}
},
WhereClause = new WhereClause
{
SearchCondition = new BooleanComparisonExpression
{
ComparisonType = BooleanComparisonType.Equals,
FirstExpression = new ColumnReferenceExpression
{
MultiPartIdentifier = new MultiPartIdentifier
{
Identifiers = { CreateIdentifier(BatchIdColumnName, QuoteType.SquareBracket) }
}
},
SecondExpression = new IntegerLiteral {
Value = batchId.ToString()
}
}
}
};
// Put together the rest of the statement
IfStatement ifNotExists = new IfStatement
{
Predicate = new BooleanNotExpression
{
Expression = existsExp
}
};
return(ifNotExists);
}
private List <TableParsingResult> ExtractTablesFromScalarSubQuery(ScalarSubquery scalarSubquery)
{
List <TableParsingResult> result = new List <TableParsingResult>();
if (scalarSubquery.QueryExpression is QuerySpecification querySpecification)
{
var items = ExtractTablesFromQuerySpecification(querySpecification);
result.AddIfNotExists(items);
}
return(result);
}
public override void Visit(ScalarSubquery node) { this.action(node); }
public override void Visit(ScalarSubquery node)
{
base.Visit(node);
Subqueries.Add(node);
}
public override void ExplicitVisit(ScalarSubquery fragment)
{
_fragments.Add(fragment);
}
public gsScalarExpressionParserScalarSubquery(ScalarExpression expression, string columnAlias)
: base(expression, columnAlias)
{
_ScalarExpression = expression as ScalarSubquery;
}
