I'm still learning some of the PL/SQL differences, so this may be an easy question, but... here goes.
I have a cursor which grabs a bunch of records with multiple fields. I then run two separate SELECT statements in a LOOP from the cursor results to grab some distances and calculate those distances. These work perfectly.
When I go to update the table with the new values, my problem is that there are four pieces of specific criteria.
update work
set kilometers = calc_kilo,
kilo_test = test_kilo
where lc = rm.lc
AND ld = rm.ld
AND le = rm.le
AND lf = rm.lf
AND code = rm.code
AND lcode = rm.lcode
and user_id = username;
My problem is that this rarely updating because rm.lf and rm.le have NULL values in the database. How can I combat this, and create the correct update.
If I'm understanding you correctly, you want to match lf with rm.lf, including when they're both null? If that's what you want, then this will do it:
...
AND (lf = rm.lf
OR (lf IS NULL AND rm.lf IS NULL)
)
...
It's comparing the values of lf and rm.lf, which will return false if either is null, so the OR condition returns true if they're both null.
I have a cursor which grabs a bunch of records with multiple fields. I then run two separate SELECT statements in a LOOP from the cursor results to grab some distances and calculate those distances. These work perfectly.
When I go to update the table with the new values, my problem is that there are four pieces of specific criteria.
The first thing I'd look at is not using a cursor to read data, then make calculations, then perform updates. In 99% of cases it's faster and easier to just run updates that do all of this in a single step
update work
set kilometers = calc_kilo,
kilo_test = test_kilo
where lc = rm.lc
AND ld = rm.ld
AND NVL(le,'x') = NVL(rm.le,'x')
AND NVL(lf,'x') = NVL(rm.lf,'x')
AND code = rm.code
AND lcode = rm.lcode
and user_id = username;
Related
I have the following situation within a PL/SLQ function. Depending of existing table field value I might run a different select. Specifically: I can have multiple rows for a particular BILL CODE (PINGPONG) where I would only need to get the SYS_FIELD value. This field has to be fetched only once according to following condition: If fields prep_seq_num=0 and primary_ind=0 then just get this row sys_field value straightaway and do not take care of other possible prep_seq_num and primary_ind values different from 0. If that rows is not existing, fetch the sys_field value from prep_seq_num!=0 and primary_ind=1. For both case only one instance/row must be possible So in the first case I should run:
SELECT SYS_FIELD
INTO v_start_of_invoice
FROM BILL
WHERE TRACKING_ID = v_previous_trackingID
AND BSCO_CODE_ID = 'PINGPONG'
AND CHRG_ACCT_ID = v_ACCT_ID
AND PREP_SEQ_NUM = 0 -- maybe not needed here
AND ITEM_CAT_CODE_ID=1
AND PARTITION_KEY = v_prev_partition
AND SUBPARTITION_KEY = v_prev_subpartition
AND PRIMARY_IND=0;
In the second case
SELECT SYS_FIELD
INTO v_start_of_invoice
FROM BILL
WHERE TRACKING_ID = v_previous_trackingID
AND BILL_CODE_ID = 'PINGPONG'
AND ITEM_CAT_CODE_ID in ('5' , '-100')
AND PARTITION_KEY = v_prev_partition
AND SUBPARTITION_KEY = v_prev_subpartition
AND PRIMARY_IND=1;
Not sure I'm making it very complicated, but still I 'd need to know whether IF THEN ELSE or CASE or whatever should be used and how.
You can utilize an implicit cursor for loop.
for rec IN ( <your query that gives all records)
LOOP
--compare the value of this variable and decide in the IF condition.
IF rec.prep_seq_num=0 and rec.primary_ind=0
THEN
-- write the query to get the sys_field
ELSE
-- write alternative query.
END IF;
END LOOP;
Beginner Lua quesiton - I'm just learning lua, and I wrote some code, a nested table to create something like a table with rows and columns.
However, when I iterate through the table using pairs(), it doesn't output in the same order I put it in. I put it in a Serial, Service Days, Connected, and it's coming out as Service Days, Serial, Connected. I am at a loss to figuring out why. I intentionally created the three rows different ways, since I'm just learning and trying to get comfortable with the different ways of dealing with Lua tables...
The code:
myTable = {}
myTable["headerRow"] = {
Serial = "Serial",
ServDays = "Service Days",
Connected = "Connected" }
myTable[1] = {
Serial = "B9FX",
ServDays = 7,
Connected = true }
myTable[2] = {}
myTable[2]["Serial"] = "2SHA"
myTable[2]["ServDays"] = 3
myTable[2]["Connected"] = true
for k, v in pairs(myTable) do
for k2, v2 in pairs(v) do
io.write(tostring(v2),",")
end
io.write("\n") --End the row
end
The result:
c:\lua>lua53 primer.lua
7,B9FX,true,
3,2SHA,true,
Service Days,Serial,Connected,
pairs uses the next function. Hence the order of traversal in a generic for loop using the pairs iterator is unspecified.
From the Lua reference manual:
https://www.lua.org/manual/5.3/manual.html#pdf-next
The order in which the indices are enumerated is not specified, even
for numeric indices. (To traverse a table in numerical order, use a
numerical for.)
The behavior of next is undefined if, during the traversal, you assign
any value to a non-existent field in the table. You may however modify
existing fields. In particular, you may clear existing fields.
If you do something like this:
myTable[2] = {}
myTable[2]["Serial"] = "2SHA"
myTable[2]["ServDays"] = 3
myTable[2]["Connected"] = true
Lua will not remember in which order you asigned values to table keys. It will only map keys to values.
I want to loop thru a dbf and create word table for each record meeting the condition, and I got a one-page report with only the last rec in a single table. Look like all records are written to the same table. I tried to use n = n + 1 to place the variable as an element to the table
oTable = oDoc.tables[n]
But seems it only support numerical rather than variable ?
You have to add each table as you go, making sure to leave space in between them (because Word likes to combine tables).
You'll need something like this inside your loop:
* Assumes you start with oDoc pointing to the document,
* oRange set to an empty range at the beginning of the area where you want to add the tables,
* and that nRows and nCols give you the size of the table.
oTable = oDoc.Tables.Add(m.oRange, m.nRows, m.nCols)
oRange = oTable.Range()
oRange.Collapse(0)
oRange.InsertParagraphAfter()
oRange.Collapse(0)
After this code, you can use oTable to add the data you want to add. Then, on the next time through the loop, you're ready to add another table below the one you just filled.
I am trying to query an XML document for the specific records that I need. I know that the line containing the "or where" case below is incorrect, but I'm hoping it will illustrate what I am trying to accomplish. Can you do a conditional where clause on two seperate properties?
XDocument xd = XDocument.Load("CardData.xml");
SearchList.ItemsSource = from x in xd.Descendants("card")
where x.Element("title").Value.ToUpper().Contains(searchterm.ToUpper())
or where x.Element("id").Value.Contains(searchterm)
select new Card
{
Title = x.Element("title").Value
};
Yes - simply use the boolean or || and combine your conditions into one Where clause:
where x.Element("title").Value.ToUpper().Contains(searchterm.ToUpper()) ||
x.Element("id").Value.Contains(searchterm)
Also note just as a minor optimization, I would pre-compute some of the operations you currently have in your Where clause so they are not performed on every item in the list - probably doesn't matter but it might when you have a lot of elements (and is just a good habit to get into in my opinion):
string searchTermUpperCase = searchterm.ToUpper();
SearchList.ItemsSource = from x in xd.Descendants("card")
where x.Element("title").Value.ToUpper().Contains(searchTermUpperCase)
or where x.Element("id").Value.Contains(searchterm)
..
Ok, say I have a query:
SELECT * FROM TABLE_AWESOME WHERE YEAR = :AMAZINGYEAR;
Which works very nicely. But say I want to be able to return either just those results or all results based on a drop down. (e.g., the drop down would have 2008, 2009, ALL YEARS)
I decided to tackle said problem with PL/SQL with the following format:
DECLARE
the_year VARCHAR(20) := &AMAZINGYEAR;
BEGIN
IF the_year = 'ALL' THEN
SELECT * FROM TABLE_AWESOME;
ELSE
SELECT * FROM TABLE_AWESOME WHERE YEAR = the_year;
END IF;
END;
Unfortunately, this fails. I get errors like "an INTO clause is expected in this SELECT statement".
I'm completely new to PL/SQL so I think I'm just expecting too much of it. I have looked over the documentation but haven't found any reason why this wouldn't work the way I have it. The query I'm actually using is much much more complicated than this but I want to keep this simple so I'll get answer quickly.
Thanks in advance :)
There is a real danger in the queries offered by Jim and Alex.
Assumption, you have 20 years of data in there, so a query on YEAR = return 5% of the blocks. I say blocks and not rows because I assume the data is being added on that date so the clustering factor is high.
If you want 1 year, you want the optimizer to use an index on year to find those 5% of rows.
If you want all years, you want the optimizer to use a full table scan to get every row.
Are we good so far?
Once you put this into production, the first time Oracle loads the query it peaks at the bind variable and formulates a plan based on that.
SO let's say the first load is 'All'.
Great, the plan is a Full table scan (FTS) and that plan is cached and you get all the rows back in 5 minutes. No big deal.
The next run you say 1999. But the plan is cached and so it uses a FTS to get just 5% of the rows and it takes 5 minutes. "Hmmm... the user says, that was many fewer rows and the same time." But that's fine... it's just a 5 minute report... life is a little slow when it doesn't have to be but no one is yelling.
That night the batch jobs blow that query out of the cache and in the morning the first user asks for 2001. Oracle checks the cache, not there, peeks at the variable, 2001. Ah, the best plan for that is an index scan. and THAT plan is cached. The results come back in 10 seconds and blows the user away. The next person, who is normally first, does the morning "ALL" report and the query never returns.
WHY?
Because it's getting every single row by looking through the index.... horrible nested loops. The 5 minute report is now at 30 and counting.
Your original post has the best answer. Two queries, that way both will ALWAYS get the best plan, bind variable peeking won't kill you.
The problem you're having is just a fundamental Oracle issue. You run a query from a tool and get the results back INTO the tool. If you put a select statement into a pl/sql block you have to do something with it. You have to load it into a cursor, or array, or variable. It's nothing to do with you being wrong and them being right... it's just a lack of pl/sql skills.
You could do it with one query, something like:
SELECT * FROM TABLE_AWESOME WHERE (? = 'ALL' OR YEAR = ?)
and pass it the argument twice.
In PL/SQL you have to SELECT ... INTO something, which you need to be able to return to the client; that could be a ref cursor as tanging demonstrates. This can complicate the client.
You can do this in SQL instead with something like:
SELECT * FROM TABLE_AWESOME WHERE :AMAZING_YEAR = 'ALL' OR YEAR = :AMAZINGYEAR;
... although you may need to take care about indexes; I'd look at the execution plan with both argument types to check it isn't doing something unexpected.
Not sure about using a SqlDataSource, but you can definately do this via the system.data.oracle or the oracle clients.
You would do this via an anonymous block in asp.net
VAR SYS1 REFCURSOR;
VAR SYS2 REFCURSOR;
DECLARE
FUNCTION CURSORCHOICE(ITEM IN VARCHAR2) RETURN SYS_REFCURSOR IS
L_REFCUR SYS_REFCURSOR;
returnNum VARCHAR2(50);
BEGIN
IF upper(item) = 'ALL' THEN
OPEN L_REFCUR FOR
SELECT level FROM DUAL
CONNECT BY LEVEL < 15 ;
ELSE
OPEN L_REFCUR FOR
SELECT 'NONE' FROM DUAL ;
END IF;
RETURN L_REFCUR;
END ;
BEGIN
:SYS1 := CURSORCHOICE('ALL');
:SYS2 := CURSORCHOICE('NOT ALL');
end ;
/
PRINT :SYS1 ;
PRINT :SYS2 ;
whereas you would simply create an output param (of type refcursor) -- instead of the var sys# refcursors) and pretty much just amend the above code.
I answered a similar question about getting an anonymous block refcuror here
How to return a RefCursor from Oracle function?
This kind of parameter shall be processed from within your code so that your OracleCommand object only executes either queries.
using (var connection = new OracleConnection(connString)) {
connection.Open();
string sql = "select * from table_awesome";
sql = string.Concat(sql, theYear.Equals(#"ALL") ? string.Empty : " where year = :pYear")
using (var command = connection.CreateCommand()) {
command.CommancText = sql;
command.CommandType = CommandType.Text;
var parameter = command.CreateParameter();
parameter.Name = #":yearParam";
parameter.Direction = ParameterDirection.Input;
parameter.Value = theYear;
var reader = command.ExecuteQuery();
if (!reader.HasRows) return;
while (reader.Read()) {
// Extract your data from the OracleDataReader instance here.
}
}
}