How can I have a where clause be based on a variable:
If I have a variable #PrintNum and it has a number I want a different where clause, but it not it is different. See below: Is this possible?
Where PrintNum = #PrintNum
Else
Where InvNum = #InvNum,
etc....
where PrintNum = #PrintNum or InvNum = #InvNum
You can chain together as many things in a where clause as you like using either or or and statements
Related
I have used the List.Accumulate() to merge mutliple tables. This is the output I've got in this simple example:
Now, I need a solution to expand all these with a formula, because in real - world I need to merge multiple tables that keep increasing in number (think Eurostat tables, for instance), and modifying the code manually wastes much time in these situations.
I have been trying to solve it, but it seems to me that the complexity of syntax easily becomes the major limitation here. For instance, If I make a new step where I nest in another List.Accumulate() the Table.ExpandTableColumns(), I need to pass inside a column name of an inner table, as a text. Fine, but to drill it down actually, I first need to pass a current column name in [] in each iteration - for instance, Column 1 - and it triggers an error if I store column names to a list because these are between "". I also experimented with TransformColumns() but didn't work either.
Does anyone know how to solve this problem whatever the approach?
See https://blog.crossjoin.co.uk/2014/05/21/expanding-all-columns-in-a-table-in-power-query/
which boils down to this function
let Source = (TableToExpand as table, optional ColumnNumber as number) =>
//https://blog.crossjoin.co.uk/2014/05/21/expanding-all-columns-in-a-table-in-power-query/
let ActualColumnNumber = if (ColumnNumber=null) then 0 else ColumnNumber,
ColumnName = Table.ColumnNames(TableToExpand){ActualColumnNumber},
ColumnContents = Table.Column(TableToExpand, ColumnName),
ColumnsToExpand = List.Distinct(List.Combine(List.Transform(ColumnContents, each if _ is table then Table.ColumnNames(_) else {}))),
NewColumnNames = List.Transform(ColumnsToExpand, each ColumnName & "." & _),
CanExpandCurrentColumn = List.Count(ColumnsToExpand)>0,
ExpandedTable = if CanExpandCurrentColumn then Table.ExpandTableColumn(TableToExpand, ColumnName, ColumnsToExpand, NewColumnNames) else TableToExpand,
NextColumnNumber = if CanExpandCurrentColumn then ActualColumnNumber else ActualColumnNumber+1,
OutputTable = if NextColumnNumber>(Table.ColumnCount(ExpandedTable)-1) then ExpandedTable else ExpandAll(ExpandedTable, NextColumnNumber)
in OutputTable
in Source
alternatively, unpivot all the table columns to get one column, then expand that value column
ColumnsToExpand = List.Distinct(List.Combine(List.Transform(Table.Column(#"PriorStepNameHere", "ValueColumnNameHere"), each if _ is table then Table.ColumnNames(_) else {}))),
#"Expanded ColumnNameHere" = Table.ExpandTableColumn(#"PriorStepNameHere", "ValueColumnNameHere",ColumnsToExpand ,ColumnsToExpand ),
Full Query:
{[tier;company;ccy; startdate; enddate] select Deal_Time, Deal_Date from DEALONLINE_REMOVED where ?[company = `All; 1b; COMPANY = company], ?[tier = `All;; TIER = tier], Deal_Date within(startdate;enddate), Status = `Completed, ?[ccy = `All;1b;CCY_Pair = ccy]}
Particular Query:
where ?[company = `All; 1b; COMPANY = company], ?[tier = `All; 1b; TIER = tier],
What this query is trying to do is to get the viewstate of a dropdown.
If there dropdown selection is "All", that where clause i.e. company or tier is invalidated, and all companies or tiers are shown.
I am unsure if the query above is correct as I am getting weird charts when displaying them on KDB dashboard.
What I would recommend is to restructure your function to make use of the where clause using functional qSQL.
In your case, you need to be able to filter based on certain input, if its "All" then don't filter else filter on that input. Something like this could work.
/Define sample table
DEALONLINE_REMOVED:([]Deal_time:10#.z.p;Deal_Date:10?.z.d;Company:10?`MSFT`AAPL`GOOGL;TIER:10?`1`2`3)
/New function which joins to where clause
{[company;tier]
wc:();
if[not company=`All;wc:wc,enlist (=;`Company;enlist company)];
if[not tier=`All;wc:wc,enlist (=;`TIER;enlist tier)];
?[DEALONLINE_REMOVED;wc;0b;()]
}[`MSFT;`2]
If you replace the input with `All you will see that everything is returned.
The full functional select for your query would be as follows:
whcl:{[tier;company;ccy;startdate;enddate]
wc:(enlist (within;`Deal_Date;(enlist;startdate;enddate))),(enlist (=;`Status;enlist `Completed)),
$[tier=`All;();enlist (=;`TIER;enlist tier)],
$[company=`All;()enlist (=;`COMPANY;enlist company)],
$[ccy=`All;();enlist (=;`CCY_Pair;enlist ccy)];
?[`DEALONLINE_REMOVED;wc;0b;`Deal_Time`Deal_Date!`Deal_Time`Deal_Date]
}
The first part specifies your date range and status = `Completed in the where clause
wc:(enlist (within;`Deal_Date;(enlist;startdate;enddate))),(enlist (=;`Status;enlist `Completed)),
Next each of these conditionals checks for `All for the TIER, COMPANY and CCY_Pair column filtering. It then joins these on to the where clause when a specific TIER, COMPANY or CCY_Pair are specified. (otherwise an empty list is joined on):
$[tier=`All;();enlist (=;`TIER;enlist tier)],
$[company=`All;();enlist (=;`COMPANY;enlist company)],
$[ccy=`All;();enlist (=;`CCY_Pair;enlist ccy)];
Finally, the select statement is called in its functional form as follows, with wc as the where clause:
?[`DEALONLINE_REMOVED;wc;0b;`Deal_Time`Deal_Date!`Deal_Time`Deal_Date]
I am facing an issue with the query in postgreSql. Below is the query.
UPDATE t_e20so1_fieldrulethen AS fthen
SET c_thenfieldid = t1.c_fieldschemaid
FROM t_sys_fieldschema AS t1
WHERE fthen.c_lyrathenfieldid = t1.c_lyraid
AND fthen.c_rulefor = 5
AND t1.c_fieldtype = 18
AND t1.c_tablegroupsid IN (
CASE
WHEN fthen.c_iffieldid = t1.c_id THEN (SELECT
c_targettableid
FROM t_sys_tablegroups
WHERE c_parentid = 'c0b2f85c-bc93-466b-a54d-b1330440db98')
ELSE (SELECT c_targettableid
FROM t_sys_tablegroups
WHERE c_parentid =
'c0b2f85c-bc93-466b-a54d-b1330440db98')
END );
As per above query, i am updating t_e20so1_fieldrulethen table from t_sys_fieldschema. One of the conditions to check is t_sys_fieldschema.c_tablegroupsid should be having specific values which are in and I am fetching them from table t_sys_tablegroups.
Above query gives me error as shown below:
ERROR: more than one row returned by a subquery used as an expression
SQL state: 21000
Here, if I remove case from the query (below is what I mean) it works properly.
UPDATE t_e20so1_fieldrulethen AS fthen
SET c_thenfieldid = t1.c_fieldschemaid
FROM t_sys_fieldschema AS t1
WHERE fthen.c_lyrathenfieldid = t1.c_lyraid
AND fthen.c_rulefor = 5
AND t1.c_fieldtype = 18
AND t1.c_tablegroupsid IN (SELECT c_targettableid
FROM t_sys_tablegroups
WHERE
c_parentid = 'c0b2f85c-bc93-466b-a54d-b1330440db98')
Now I have only one select query in the "IN" clause.
I've checked that kind of case statement(two nested selects) - and it cannot be done that way. You generate two separate lists in one CASE.
One list for all records where fthen.c_iffieldid = t1.c_id and the other for ELSE statement.
As I wrote many times never use nested selects in "IN" clause. It is killing performance and causing many problems. Use "EXISTS".
As your CASE seems to be redundant (both WHEN and ELSE returns same value) change it that way and it will be faster.
UPDATE t_e20so1_fieldrulethen AS fthen
SET c_thenfieldid = t1.c_fieldschemaid
FROM t_sys_fieldschema AS t1
WHERE fthen.c_lyrathenfieldid = t1.c_lyraid
AND fthen.c_rulefor = 5
AND t1.c_fieldtype = 18
AND exists (select from t_sys_tablegroups t2
where t1.c_tablegroupsid=t2.c_targettableid
and c_parentid = 'c0b2f85c-bc93-466b-a54d-b1330440db98');
I tried looking for an example of using Arel::UpdateManager to form an update statement with a from clause (as in UPDATE t SET t.itty = "b" FROM .... WHERE ...), couldn.t find any. The way I've seen it, Arel::UpdateManager sets the main engine on initialization and allows to set the various fields and values to update. Is there actually a way to do this?
Another aside would be to find out how to express Postgres posix regex matching into ARel, but this might be impossible by now.
As far as I see the current version of arel gem is not support FROM keyword for the sql query. You can generate a query using the SET, and WHERE keywords only, like:
UPDATE t SET t.itty = "b" WHERE ...
and the code, which copies a value from field2 to field1 for the units table, will be like:
relation = Unit.all
um = Arel::UpdateManager.new(relation.engine)
um.table(relation.table)
um.ast.wheres = relation.wheres.to_a
um.set(Arel::Nodes::SqlLiteral.new('field1 = "field2"'))
ActiveRecord::Base.connection.execute(um.to_sql)
Exactly you can use the additional method to update a relation. So we create the Arel's UpdateManager, assigning to it the table, where clause, and values to set. Values shell be passed to the method as an argument. Then we need to add FROM keyword to the generated SQL request, we add it only if we have access to external table of the specified one by the UPDATE clause itself. And at the last we executes the query. So we get:
def update_relation!(relation, values)
um = Arel::UpdateManager.new(relation.engine)
um.table(relation.table)
um.ast.wheres = relation.wheres.to_a
um.set(values)
sql = um.to_sql
# appends FROM field to the query if needed
m = sql.match(/WHERE/)
tables = relation.arel.source.to_a.select {|v| v.class == Arel::Table }.map(&:name).uniq
tables.shift
sql.insert(m.begin(0), "FROM #{tables.join(",")} ") if m && !tables.empty?
# executes the query
ActiveRecord::Base.connection.execute(sql)
end
The you can issue the the relation update as:
values = Arel::Nodes::SqlLiteral.new('field1 = "field2", field2 = NULL')
relation = Unit.not_rejected.where(Unit.arel_table[:field2].not_eq(nil))
update_relation!(relation, values)
When you retrieve data through a MySQLi statement such as the following:
$sqls = "SELECT * FROM course WHERE course='$product_id_array' OR course='Both' ORDER BY ...";
$sqlsresults = mysqli_query($db_conx,$sqls);
while($row = mysqli_fetch_assoc($sqlsresults)) {
$selectedContent = $row["content"];
$selectedTitle = $row["title"];
}
Is there a way to output the match for 'both' first? Would this be as simple as re-arranging the order of the WHERE portion of the statement?
Your ORDER BY explicitly sorts only by id. There is no way around this in the WHERE part of your query. To change how results are ordered, use ORDER BY.
SELECT *
FROM course
WHERE course=...
OR course='Both'
ORDER BY CASE course WHEN 'Both' THEN 0 ELSE 1 END ASC, id DESC
Unrelated note: if $product_id_array contains untrusted user input, the user can put things like '; DELETE FROM course; -- in there. Read up on parameterized queries to learn how to prevent that.