I am having some trouble in converting the following
SELECT * FROM foo f WHERE
(f.name = 'name' AND f.date = '1980/02/2001')
OR
(f.name = 'another name' AND f.date = '1990/02/2001')
to
new Select().From(Foo.Schema.TableName)
.Where(Foo.Columns.Name).IsEqualTo('name')
.And(Foo.Columns.Date).IsEqualTo('1980/02/2001')
.Or(Foo.Columns.Name).IsEqualTo('another name')
.And(Foo.Columns.Date).IsEqualTo('1990/02/2001')
as you can see I am not aware of the method which can isolate two groups of "AND" and put each of them in an "OR" statement.
I would really appreciate your help in this context.
You need to wrap the parts in barckets using the .AndExpression() and .CloseExpression()
See: http://biasecurities.com/2008/07/complex-sql-conditional-statements-with-subsonic-2-1/ for examples
Related
In the description of filtering records in Peewee, there are examples of two alternative syntaxes: using commas to separate multiple conditions, such as the following example,
Tweet.select().where(Tweet.user == user, Tweet.is_published == True)
and using bitwise operators. I cannot figure out (and cannot find a description of) the difference between using the comma syntax and using bitwise operators. What does the comma syntax actually do? From the (single) documented example of using a comma, it seems like it might be equivalent to using &, as in
Tweet.select().where( (Tweet.user == user) & (Tweet.is_published == True) )
Is that the case?
Yes, they are equivalent, as per the code:
def where(self, *expressions):
if self._where is not None:
expressions = (self._where,) + expressions
self._where = reduce(operator.and_, expressions)
I am stuck to find out better one between str() and format() in python
"SELECT schools.deis_income , schools.school_name,SUM(money.coin_in_amount) AS coinamount, SUM(money.note_in_amount) AS noteamount , SUM(money.coffee_coin_in_amount) AS coffeeamount , SUM(money.coin_out_amount) AS coinoutamount, SUM(money.note_out_amount) AS noteoutamount FROM money_transactions AS money JOIN school_admin_details AS sa on sa.id = money.school_admin_id JOIN schools ON schools.id=sa.school_id WHERE sa.school_id ={school_id} AND money.transaction_time BETWEEN '{start_date}' AND '{end_date}' GROUP BY schools.id".format(school_id=school_id,start_date=start_date,end_date=end_date)
I use format function here. can I use str() ?
please tell me which one give me quick result, str() or format() ???
If your question is which of this:
foo = "some text " + str(some_var) + " and some other text"
or this:
foo = "some text {} and some other text".format(var)
is "better", the general consensus is very clear: string formatting is much easier to read and maintain and the one pythonic way to go.
Now for your particular example, the answer is that both are totally wrong - unless you're ok to give full access to your database to even the most inept script kiddie. For SQL queries, the proper solution is to use prepared statements, where your db connector will take care of proper formatting and sanitizing of the values:
# assumes MySQL - for other vendors check your own
# db-api connector's doc for the correct placeholder
query = "SELECT somefield FROM mytable where somedate > %(somedate)s and something_else = %(someval)s"
cursor.execute(query, {"somedate": some_date, "someval": 42})
I am using cascaded filters in my reports and I have my expression like below -
if ([Region] = "${whichRegion}",[State],null)
along with the above expression, I would like to preselect one of the values of [state] column.
i would need some thing like this -
if ([Region] = "${whichRegion}",[State],null)
or
[State] = 'some default value'
I know above expression throws error.
Could you please let me know how the above expression can be modified ?
Just place your default state value in your false clause.
if([Region] = "${whichRegion}",[State],"DefaultStateValue")
BTW, where are you using this expression at?
I have a field named field, and I would like to see if it is null, but I get an error in the query, my code is this:
let
Condition= Excel.CurrentWorkbook(){[Name="test_table"]}[Content],
field= Condition{0}[fieldColumn],
query1="select * from students",
if field <> null then query1=query1 & " where id = '"& field &"',
exec= Oracle.Database("TESTING",[Query=query1])
in
exec
but I get an error in the condition, do you identify the mistake?
I got Expression.SyntaxError: Token Identifier expected.
You need to assign the if line to a variable. Each M line needs to start with an assignment:
let
Condition= Excel.CurrentWorkbook(){[Name="test_table"]}[Content],
field= Condition{0}[fieldColumn],
query1="select * from students",
query2 = if field <> null then query1 & " some stuff" else " some other stuff",
exec= Oracle.Database("TESTING",[Query=query2])
in
exec
In query2 you can build the select statement. I simplified it, because you also have conflicts with the double quotes.
I think you're looking for:
if Not IsNull(field) then ....
Some data types you may have to check using IsEmpty() or 'field is Not Nothing' too. Depending on the datatype and what you are using.
To troubleshoot, it's best to try to set a breakpoint and locate where the error is happening and watch the variable to prevent against that specific value.
To meet this requirement, I would build a fresh Query using the PQ UI to select the students table/view from Oracle, and then use the UI to Filter the [id] column on any value.
Then in the advanced editor I would edit the generated FilteredRows line using code from your Condition + field steps, e.g.
FilteredRows = Table.SelectRows(TESTING_students, each [id] = Excel.CurrentWorkbook(){[Name="test_table"]}{0}[fieldColumn])
This is a minor change from a generated script, rather than trying to write the whole thing from scratch.
This is my first question on the forum, but reading previous questions has been enormously helpful in the project I'm working on, so already my thanks. I couldn't find an answer to this, but apologies if I overlooked something.
I am writing an excel macro in vba, and am trying to create a select case... statement in which the expression has a variable boolean and numeric component. For example, the macro can pull "> 3" or "< 3" from another worksheet.
My hope had been that I could assign to a string all of these parameters, i.e.:
test1 = "is " & BoolOperator1 & " " & NumericValue1
and then
Select case ValuetoCompare
Case test1
'Do something
Case test2
'...
Is there a way to do this? I suppose the alternative would be to nest the case with the numeric variable inside a select function that determines the operator, but I thought this would be more elegant.
Thanks in advance for your guidance--
Josh
Assuming that you'll get a string BoolOperator1 that is a valid operator, e.g. >=, =, and a numeric value NumericValue1, the easiest way to execute this comparison on another numeric value ValueToCompare is to use the Evaluate function. This will execute a string as VBA and return it's result.
In your case, you could simply use:
If Evaluate(ValueToCompare&BoolOperator1&NumericValue1) Then ...
If you want to use this in a Select Case statement, you'd either need to use a simple If ... ElseIf ... statement - or use this trick:
Select Case True
Case Evaluate(ValueToCompare&BoolOperator1&NumericValue1): ...
Case Evaluate(ValueToCompare&BoolOperator2&NumericValue2): ...
Case Else ...
End Select