I am changing pg-pool to cater cypher queries for Apache AGE and I have the following code, which takes the select statement. From that it gets the FROM clause, then from the FROM clause it gets the function names. So now I want that function arguments also. How would I do that. The code is as follows:
if (IsA(node, SelectStmt))
{
SelectStmt *stmt = (SelectStmt *) node;
List* fromClause = stmt->fromClause;
ListCell *fl;
//Match the first cypher function call in the FROM clause. Could be multiple tables
// e.g. FROM table1, table2, cypher(),table3....
foreach(fl, fromClause)
{
Node *n = lfirst(fl);
if (IsA(n, RangeFunction))
{
RangeFunction *rf = (RangeFunction*) n;
List* functions = rf->functions;
if (functions->length == 1)
{
List *sublist = (List *) lfirst(list_head(functions));
FuncCall *fntree = (FuncCall *) lfirst(list_head(sublist));
StringInfoData str;
initStringInfo(&str);
_outNode(&str,fntree->funcname);
if (!strcmp("\"cypher\"",str.data)){
return true;
}
}
}
}
}
The arguments are stored in FuncCall. Since you already have that, you can get them with
fntree->args
Note that your code only covers function calls in the top FROM list. What if there are subqueries?
Related
I am using Scala 2.11.8
I am trying to read queries from my Property File. Each Query Set has multiple parts (explained below)
And i have certain sequence in which these queries must execute.
Code:
import com.typesafe.config.ConfigFactory
object ReadProperty {
def main(args : Array[String]): Unit = {
val queryRead = ConfigFactory.load("testqueries.properties").getConfig("select").getStringList("caseInc").toArray()
val localRead = ConfigFactory.load("testqueries.properties").getConfig("select").getStringList("caseLocal").toArray.toSet
queryRead.foreach(println)
localRead.foreach(println)
}
}
PropertyFile Content :
select.caseInc.2 = Select emp_salary, emp_dept_id from employees
select.caseLocal.1 = select one
select.caseLocal.3 = select three
select.caseRemote.2 = Select e1.emp_name, d1.dept_name, e1.salary from emp_1 e1 join dept_1 d1 on(e1.emp_dept_id = d1.dept_id)
select.caseRemote.1 = Select * from departments
select.caseInc.1 = Select emp_id, emp_name from employees
select.caseLocal.2 = select two
select.caseLocal.4 = select four
Output:
Select emp_id, emp_name from employees
Select emp_salary, emp_dept_id from employees
select one
select two
select three
select four
As we can see in output, The result is Sorted . In the property if you see i have tried numbering the queries in the sequence it should run.(passing the caseInc, caseLocal as arguments).
With getStringList() i am always getting the Sorted List on the basis of the sequence number i am providing.
Even when i tried using toArray() & toArray().toSet i am getting sorted output.
So far its Good
But how to be sure that it will always return in Sorted Order which i have provided in the property file. I am confused because somehow i am not able to find the API which says that the returned List will be Sorted.
I think you can rely on this fact. Looking into the code of DefaultTransformer you can see following piece of logic:
} else if (requested == ConfigValueType.LIST && value.valueType() == ConfigValueType.OBJECT) {
// attempt to convert an array-like (numeric indices) object to a
// list. This would be used with .properties syntax for example:
// -Dfoo.0=bar -Dfoo.1=baz
// To ensure we still throw type errors for objects treated
// as lists in most cases, we'll refuse to convert if the object
// does not contain any numeric keys. This means we don't allow
// empty objects here though :-/
AbstractConfigObject o = (AbstractConfigObject) value;
Map<Integer, AbstractConfigValue> values = new HashMap<Integer, AbstractConfigValue>();
for (String key : o.keySet()) {
int i;
try {
i = Integer.parseInt(key, 10);
if (i < 0)
continue;
values.put(i, o.get(key));
} catch (NumberFormatException e) {
continue;
}
}
if (!values.isEmpty()) {
ArrayList<Map.Entry<Integer, AbstractConfigValue>> entryList = new ArrayList<Map.Entry<Integer, AbstractConfigValue>>(
values.entrySet());
// sort by numeric index
Collections.sort(entryList,
new Comparator<Map.Entry<Integer, AbstractConfigValue>>() {
#Override
public int compare(Map.Entry<Integer, AbstractConfigValue> a,
Map.Entry<Integer, AbstractConfigValue> b) {
return Integer.compare(a.getKey(), b.getKey());
}
});
// drop the indices (we allow gaps in the indices, for better or
// worse)
ArrayList<AbstractConfigValue> list = new ArrayList<AbstractConfigValue>();
for (Map.Entry<Integer, AbstractConfigValue> entry : entryList) {
list.add(entry.getValue());
}
return new SimpleConfigList(value.origin(), list);
}
}
Note how keys are parsed as integer values and then sorted using Integer.compare
Need to sort/order a list of data based on an undetermined number of columns (1 or more).
What i'm trying to do is loop through the desired columns and add an OrderBy or ThenBy based on their number to the query'd list, but i'm unsuccessful...
Done this, but it doesn't compile:
var query = GetAllItems(); //returns a IQueriable list of items
//for each selected column
for (int i = 0; i < param.Columns.Length; i++)
{
if (i == 0)
{
query = query.OrderBy(x => x.GetType().GetProperty(param.Columns[i].Name));
}
else
{
//ERROR: IQueriable does not contain a definition for "ThenBy" and no extension method "ThenBy"...
query = query.ThenBy(x => x.GetType().GetProperty(param.Columns[i].Data));
}
}
How can i resolve this issue? Or any alternative to accomplish this requirement?
SOLUTION: #Dave-Kidder's solution is well thought and resolves the compile errors i had. Just one problem, OrderBy only executes (actually sorts the results) after a ToList() cast. This is an issue because i can't convert a ToList back to an IOrderedQueryable.
So, after some research i came across a solution that resolve all my issues.
Microsoft assembly for the .Net 4.0 Dynamic language functionality: https://github.com/kahanu/System.Linq.Dynamic
using System.Linq.Dynamic; //need to install this package
Updated Code:
var query = GetAllItems(); //returns a IQueriable list of items
List<string> orderByColumnList = new List<string>(); //list of columns to sort
for (int i = 0; i < param.Columns.Length; i++)
{
string column = param.Columns[i].Name;
string direction = param.Columns[i].Dir;
//ex.: "columnA ASC"
string orderByColumn = column + " " + direction;
//add column to list
orderByColumnList.Add(orderBy);
}
//convert list to comma delimited string
string orderBy = String.Join(",", orderByColumnList.ToArray());
//sort by all columns, yay! :-D
query.OrderBy(orderBy).ToList();
The problem is that ThenBy is not defined on IQueryable, but on the IOrderedQueryable interface (which is what IQueryable.OrderBy returns). So you need to define a new variable for the IOrderedQueryable in order to do subsequent ThenBy calls. I changed the original code a bit to use System.Data.DataTable (to get a similar structure to your "param" object). The code also assumes that there is at least one column in the DataTable.
// using System.Data.DataTable to provide similar object structure as OP
DataTable param = new DataTable();
IQueryable<DataTable> query = new List<DataTable>().AsQueryable();
// OrderBy returns IOrderedQueryable<TSource>, which is the interface that defines
// "ThenBy" so we need to assign it to a different variable if we wish to make subsequent
// calls to ThenBy
var orderedQuery = query.OrderBy(x => x.GetType().GetProperty(param.Columns[0].ColumnName));
//for each other selected column
for (int i = 1; i < param.Columns.Count; i++)
{
orderedQuery = orderedQuery.ThenBy(x => x.GetType().GetProperty(param.Columns[i].ColumnName));
}
you should write ThenBy after OrderBy like this:
query = query
.OrderBy(t=> // your condition)
.ThenBy(t=> // next condition);
I'm updating a Qt software, to make it compatible with both SQLite and PostgreSQL.
I have a C++ method that is used to count elements of a given table with given clauses.
In SQLite, the following worked and gave me a number N (the count).
SELECT COUNT(*) FROM table_a
INNER JOIN table_b AS
ON table_b.fk_table_a = table_a.id
WHERE table_a.start_date_time <> 0
ORDER BY table_a.creation_date_time DESC
With PostgreSQL (I'm using 9.3), I have the following error :
ERROR: column "table_a.creation_date_time" must appear in the
GROUP BY clause or be used in an aggregate function
LINE 5: ORDER BY
table_a.creation_date_time DESC
If I add, GROUP BY table_a.creation_date_time, it gives me a table with N rows.
I've read a lot of stuff about how different DBMS allow you to omit columns in the GROUP BY clause. Now, I'm just confused.
For those who are curious, the C++ method is:
static int count(const QString &table, const QString &clauses = QString(""))
{
int success = -1;
if (!table.isEmpty())
{
QString statement = QString("SELECT COUNT(*) FROM ");
statement.append(table);
if (!clauses.isEmpty())
{
statement.append(" ").append(clauses) ;
}
QSqlQuery query;
if(!query.exec(statement))
{
qWarning() << query.lastError();
qWarning() << statement;
}
else
{
if (query.isActive() && query.isSelect() && query.first())
{
bool ok = false;
success = query.value(0).toInt(&ok);
if (ok == false)
{
success = -1;
return success;
}
}
}
}
return success;
}
If you're just doing a count(*) on the table in order to get a single scalar-value result, then surely having the order by present is obsolete ?
solution
Remove the obsolete order by to get "standard" query behavior across multiple dbms
*Mongo Newbie here
I have a document containing several hundred numeric fields which I need to query in combination.
var collection = _myDB.GetCollection<MyDocument>("collection");
IMongoQuery mongoQuery; // = Query.GT("field", value1).LT(value2);
foreach (MyObject queryObj in Queries)
{
// I have several hundred fields such as Height, that are in queryObj
// how do I build a "boolean" query in C#
mongoQuery = Query.GTE("Height", Convert.ToInt16(queryObj.Height * lowerbound));
}
I have several hundred fields such as Height (e.g. Width, Area, Perimeter etc.), that are in queryObj how do I build a "boolean" query in C# that combines range queries for each field in conjunction.
I have tried to use the example Query.GT("field", value1).LT(value2);, however the compiler does not accept the LT(Value) construct. In any event I need to be able to build a complex boolean query by looping through each of the numeric field values.
Thanks for helping a newbie out.
EDIT 3:
Ok, it looks like you already have code in place to build the complicated query. In that case, you just needed to fix the compiler issue. Am assuming you want to do the following (x > 20 && x < 40) && (y > 30 && y < 50) ...
var collection = _myDB.GetCollection<MyDocument>("collection");
var queries = new List<IMongoQuery>();
foreach (MyObject queryObj in Queries)
{
//I have several hundred fields such as Height, that are in queryObj
//how do I build a "boolean" query in C#
var lowerBoundQuery = Query.GTE("Height", Convert.ToInt16(queryObj.Height * lowerbound));
var upperBoundQuery = Query.LTE("Height", Convert.ToInt16(queryObj.Height * upperbound));
var query = Query.And(lowerBoundQuery, upperBoundQuery);
queries.Add(query);
}
var finalQuery = Query.And(queries);
/*
if you want to instead do an OR,
var finalQuery = Query.Or(queries);
*/
Original Answer.
var list = _myDb.GetCollection<MyDoc>("CollectionName")
.AsQueryable<MyDoc>()
.Where(x =>
x.Height > 20 &&
x.Height < 40)
.ToList();
I have tried to use the example Query.GT("field", value1).LT(value2);,
however the compiler does not accept the LT(Value) construct.
You can query MongoDB using linq, if you are using the official C# driver. That ought to solve the compiler issue I think.
The more interesting question I have in mind is, how are you going to construct that complicated boolean query?
One option is to dynamically build an Expression and then pass that to the Where
My colleague is using the following code for something similar...
public static IQueryable<T> Where<T>(this IQueryable<T> query,
string column, object value, WhereOperation operation)
{
if (string.IsNullOrEmpty(column))
return query;
ParameterExpression parameter = Expression.Parameter(query.ElementType, "p");
MemberExpression memberAccess = null;
foreach (var property in column.Split('.'))
memberAccess = MemberExpression.Property
(memberAccess ?? (parameter as Expression), property);
//change param value type
//necessary to getting bool from string
ConstantExpression filter = Expression.Constant
(
Convert.ChangeType(value, memberAccess.Type)
);
//switch operation
Expression condition = null;
LambdaExpression lambda = null;
switch (operation)
{
//equal ==
case WhereOperation.Equal:
condition = Expression.Equal(memberAccess, filter);
lambda = Expression.Lambda(condition, parameter);
break;
//not equal !=
case WhereOperation.NotEqual:
condition = Expression.NotEqual(memberAccess, filter);
lambda = Expression.Lambda(condition, parameter);
break;
//string.Contains()
case WhereOperation.Contains:
condition = Expression.Call(memberAccess,
typeof(string).GetMethod("Contains"),
Expression.Constant(value));
lambda = Expression.Lambda(condition, parameter);
break;
}
MethodCallExpression result = Expression.Call(
typeof(Queryable), "Where",
new[] { query.ElementType },
query.Expression,
lambda);
return query.Provider.CreateQuery<T>(result);
}
public enum WhereOperation
{
Equal,
NotEqual,
Contains
}
Currently it only supports == && !=, but it shouldn't be that difficult to implement >= or <= ...
You could get some hints from the Expression class: http://msdn.microsoft.com/en-us/library/system.linq.expressions.expression.aspx
EDIT:
var props = ["Height", "Weight", "Age"];
var query = _myDb.GetCollection<MyDoc>("CName").AsQueryable<MyDoc>();
foreach (var prop in props)
{
query = query.Where(prop, GetLowerLimit(queryObj, prop), WhereOperation.Between, GetUpperLimit(queryObj, prop));
}
// the above query when iterated over, will result in a where clause that joins each individual `prop\condition` with an `AND`.
// The code above will not compile. The `Where` function I wrote doesnt accept 4 parameters. You will need to implement the logic for that yourself. Though it ought to be straight forward I think...
EDIT 2:
If you don't want to use linq, you can still use Mongo Query. You will just need to craft your queries using the Query.And() and Query.Or().
// I think this might be deprecated. Please refer the release notes for the C# driver version 1.5.0
Query.And(Query.GTE("Salary", new BsonDouble(20)), Query.LTE("Salary", new BsonDouble(40)), Query.GTE("Height", new BsonDouble(20)), Query.LTE("Height", new BsonDouble(40)))
// strongly typed version
new QueryBuilder<Employee>().And(Query<Employee>.GTE(x => x.Salary, 40), Query<Employee>.LTE(x => x.Salary, 60), Query<Employee>.GTE(x => x.HourlyRateToClients, 40), Query<Employee>.LTE(x => x.HourlyRateToClients, 60))
I'm using entity framework 4.
I have a stored procedure that just updates one value in my table, namely the application state ID. So I created a stored procedure that looks like this:
ALTER PROCEDURE [dbo].[UpdateApplicationState]
(
#ApplicationID INT,
#ApplicationStateID INT
)
AS
BEGIN
UPDATE
[Application]
SET
ApplicationStateID = #ApplicationStateID
WHERE
ApplicationID = #ApplicationID;
END
I created a function import called UpdateApplicationState. I had initially set its return type to null, but then it wasn't created in the context. So I changed its return type to int. Now it was created in the context. Is it wise to return something from my stored procedure?
Here is my method in my ApplicationRepository class:
public void UpdateApplicationState(int applicationID, int applicationStateID)
{
var result = context.UpdateApplicationState(applicationID, applicationStateID);
}
Here is my calling code to this method in my view:
applicationRepository.UpdateApplicationState(id, newApplicationStateID);
When I run it then I get the following error:
The data reader returned by the store
data provider does not have enough
columns for the query requested.
Any idea/advise on what I can do to get this to work?
Thanks
To get POCO to work with function imports that return null, you can customize the .Context.tt file like this.
Find the "Function Imports" named region (the section that starts with region.Begin("Function Imports"); and ends with region.End();) in the .Context.tt file and replace that whole section with the following:
region.Begin("Function Imports");
foreach (EdmFunction edmFunction in container.FunctionImports)
{
var parameters = FunctionImportParameter.Create(edmFunction.Parameters, code, ef);
string paramList = String.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray());
var isReturnTypeVoid = edmFunction.ReturnParameter == null;
string returnTypeElement = String.Empty;
if (!isReturnTypeVoid)
returnTypeElement = code.Escape(ef.GetElementType(edmFunction.ReturnParameter.TypeUsage));
#>
<# if (isReturnTypeVoid) { #>
<#=Accessibility.ForMethod(edmFunction)#> void <#=code.Escape(edmFunction)#>(<#=paramList#>)
<# } else { #>
<#=Accessibility.ForMethod(edmFunction)#> ObjectResult<<#=returnTypeElement#>> <#=code.Escape(edmFunction)#>(<#=paramList#>)
<# } #>
{
<#
foreach (var parameter in parameters)
{
if (!parameter.NeedsLocalVariable)
{
continue;
}
#>
ObjectParameter <#=parameter.LocalVariableName#>;
if (<#=parameter.IsNullableOfT ? parameter.FunctionParameterName + ".HasValue" : parameter.FunctionParameterName + " != null"#>)
{
<#=parameter.LocalVariableName#> = new ObjectParameter("<#=parameter.EsqlParameterName#>", <#=parameter.FunctionParameterName#>);
}
else
{
<#=parameter.LocalVariableName#> = new ObjectParameter("<#=parameter.EsqlParameterName#>", typeof(<#=parameter.RawClrTypeName#>));
}
<#
}
#>
<# if (isReturnTypeVoid) { #>
base.ExecuteFunction("<#=edmFunction.Name#>"<#=code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()))#>);
<# } else { #>
return base.ExecuteFunction<<#=returnTypeElement#>>("<#=edmFunction.Name#>"<#=code.StringBefore(", ", String.Join(", ", parameters.Select(p => p.ExecuteParameterName).ToArray()))#>);
<# } #>
}
<#
}
region.End();
What I'm doing here is instead of ignoring all function imports that return null, I'm creating a method that returns null. I hope this is helpful.
It is because you do not actually returning anything from your stored procedure. Add a line like below to your SP (SELECT ##ROWCOUNT), and it will be executing properly.
BEGIN
...
SELECT ##ROWCOUNT
END
While this solution will address your issue and actually returns the number of effected rows by your SP, I am not clear on why this is an issue for you:
I had initially set its return type to null, but then it wasn't created in the context.
When doing a Function Import, you can select "None" as return type and it will generate a new method on your ObjectContext with a return type of int. This method basically executes a stored procedure that is defined in the data source; discards any results returned from the function; and returns the number of rows affected by the execution.
EDIT: Why a Function without return value is ignored in a POCO Scenario:
Drilling into ObjectContext T4 template file coming with ADO.NET C# POCO Entity Generator reveals why you cannot see your Function in your ObjectContext class: Simply it's ignored! They escape to the next iteration in the foreach loop that generates the functions.
The workaround for this is to change the T4 template to actually generate a method for Functions without return type or just returning something based on the first solution.
region.Begin("Function Imports");
foreach (EdmFunction edmFunction in container.FunctionImports)
{
var parameters = FunctionImportParameter.Create(edmFunction.Parameters, code, ef);
string paramList = String.Join(", ", parameters.Select(p => p.FunctionParameterType + " " + p.FunctionParameterName).ToArray());
// Here is why a Function without return value is ignored:
if (edmFunction.ReturnParameter == null)
{
continue;
}
string returnTypeElement = code.Escape(ef.GetElementType(edmFunction.ReturnParameter.TypeUsage));
...