Mind-boggling results of a simple query - sql

Not sure how to explain it, unless this is a bug. I'm using VFP OLEDB driver to connect to a DBF database and trying to run the following query:
SELECT id FROM MyDBF WHERE (id > 21800) AND (id < 21820)
I get the following results (copying them on one line to save space):
21810, 21811, 21812, 21813, 21814, 21815, 21816, 21817, 21818, 21819
Now I change the query slightly:
SELECT id FROM MyDBF WHERE (id > 21810) AND (id < 21820)
You expect it to return all of the IDs from previous result except the first one. Booo! The query doesn't return any rows.
Just to make sure I'm not sleepy, I run the following query
SELECT id FROM MyDBF WHERE (id = 21817)
Should return a row, but it doesn't. Not sure what's going on. I have checked the field type and it is OleDbType.Numeric.
So is this me or MS?

I'm posting the workaround I found here to help any future readers. Many thanks to Oleg for his helping hand.
Using INT(id) = 21817 instead of id = 21817 appears to work. Other versions of the SQL statement such as INT(id) BETWEEN x AND y and INT(id) > x AND INT(id) < y also appear to work fine. There's probably some discrepancy between the NUMERIC data type of FoxPro and the way OLEDB driver treats it.

Related

How can I execute a custom function in Microsoft Visual FoxPro 9?

Using Microsoft Visual FoxPro 9, I have a custom function, "newid()", inside of the stored procedures for Main:
function newId
parameter thisdbf
regional keynm, newkey, cOldSelect, lDone
keynm=padr(upper(thisdbf),50)
cOldSelect=alias()
lDone=.f.
do while not lDone
select keyvalue from main!idkeys where keyname=keynm into array akey
if _tally=0
insert into main!idkeys (keyname) value (keynm)
loop
endif
newkey=akey+1
update main!idkeys set keyvalue=newkey where keyname=keynm and keyvalue=akey
if _tally=1
lDone=.t.
endif
enddo
if not empty(cOldSelect)
select &cOldSelect
else
select 0
endif
return newkey
This function is used to generate a new ID for records added to the database.
It is called as the default value:
I would like to call this newid() function and retrieve its returned value. When executing SELECT newid("TABLENAME"), the error is is thrown:
Invalid subscript reference
How can I call the newid() function and return the newkey in Visual FoxPro 9?
As an addition to what Stefan Wuebbe said,
You actually had your answer in your previous question here that you forgot to update.
From your previous question, as I understand you are coming from a T-SQL background. While in T-SQL (and in SQL generally) there is:
Select < anyVariableOrFunction >
that returns a single column, single row result, in VFP 'select' like that has another meaning:
Select < aliasName >
aliasName is an alias of a working area (or it could be number of a work area) and is used to change the 'current workarea'. When it was used in xBase languages like FoxPro (and dBase), those languages didn't yet meet ANSI-SQL if I am not wrong. Anyway, in VFP there are two Select, this one and SELECT—SQL which definitely requires a FROM clause.
VFP has direct access to variables and function calls though, through the use of = operator.
SELECT newid("TABLENAME")
in T-SQL, would be (you are just displaying the result):
? newid("TABLENAME")
To store it in a variable, you would do something like:
local lnId
lnId = newid("TABLENAME")
* do something with m.lnId
* Note the m. prefix, it is a built-in alias for memory variables
After having said all these, as per your code.
It looks like it has been written by a very old FoxPro programmer and I must admit I am seeing it the first time in my life that someone used "REGIONAL" keyword in VFP. It is from FoxPro 2.x days I know but I didn't see anyone use it up until now :) Anyway, that code doesn't seem to be robust enough in a multiuser environment, you might want to change it. VFP ships with a NewId sample code and below is the slightly modified version that I have been using in many locations and proved to be reliable:
Function NewID
Lparameters tcAlias,tnCount
Local lcAlias, lnOldArea, lcOldReprocess, lcTable, lnTagNo, lnNewValue, lnLastValue, lcOldSetDeleted
lnOldArea = Select()
lnOldReprocess = Set('REPROCESS')
* Uppercase Alias name
lcAlias = Upper(Iif(Parameters() = 0, Alias(), tcAlias))
* Lock reprocess - try once
Set Reprocess To 1
If !Used("IDS")
Use ids In 0
Endif
* If no entry yet create
If !Seek(lcAlias, "Ids", "tablename")
Insert Into ids (tablename, NextID) Values (lcAlias,0)
Endif
* Lock, increment id, unlock, return nextid value
Do While !Rlock('ids')
* Delay before next lock trial
lnStart = Seconds()
Do While Seconds()-lnStart < 0.01
Enddo
Enddo
lnLastValue = ids.NextID
lnNewValue = m.lnLastValue + Evl(m.tnCount,1)
*Try to query primary key tag for lcAlias
lcTable = Iif( Used(lcAlias),Dbf(lcAlias), Iif(File(lcAlias+'.dbf'),lcAlias,''))
lcTable = Evl(m.lcTable,m.lcAlias)
If !Empty(lcTable)
Use (lcTable) In 0 Again Alias '_GetPKKey_'
For m.lnTagNo=1 To Tagcount('','_GetPKKey_')
If Primary(m.lnTagNo,'_GetPKKey_')
m.lcOldSetDeleted = Set("Deleted")
Set Deleted Off
Select '_GetPKKey_'
Set Order To Tag (Tag(m.lnTagNo,'_GetPKKey_')) ;
In '_GetPKKey_' Descending
Locate
lnLastValue = Max(m.lnLastValue, Evaluate(Key(m.lnTagNo,'_GetPKKey_')))
lnNewValue = m.lnLastValue + Evl(m.tnCount,1)
If Upper(m.lcOldSetDeleted) == 'ON'
Set Deleted On
Endif
Exit
Endif
Endfor
Use In '_GetPKKey_'
Select ids
Endif
* Increment
Replace ids.NextID With m.lnNewValue In 'ids'
Unlock In 'ids'
Select (lnOldArea)
Set Reprocess To lnOldReprocess
Return ids.NextID
Endfunc
Note: If you use this, as I see from your code, you would need to change the "id table" name to idkeys, field names to keyname, keyvalue:
ids => idKeys
tablename => keyName
nextId => keyValue
Or in your database just create a new table with this code:
CREATE TABLE ids (TableName c(50), NextId i)
INDEX on TableName TAG TableName
When executing SELECT newid("TABLENAME")
The error: Invalid subscript reference is thrown
The SQL Select command in Vfp requires a From clause.
Running a procedure or a function can, or better usually needs to be done differently:
For example, in the IDE's Command Window you can do a
? newid("xy") && the function must be "in scope",
&& i.e in your case the database that contains the "Stored
&& Procedure" must have been opened in advance
&& or you store the function result in a variable
Local lnNextID
lnNextID = newid("xy")
Or you can use it in an SQL SELECT when you have a From alias
CREATE CURSOR placebo (col1 Int)
INSERT INTO placebo VALUES (8)
Select newid("xy") FROM placebo

HSQL - Adding a new column in the query based on an IF condition

I need to generate a column, where in each row it checks if the Bestand is less than, equal or greater than Minbestand. If so the new column called Bestandsbewertung needs to give out Mangel, Mindestbestand or Überfluß respectively.
SELECT IF(Bestand < Minbestand, 'Mangel', IF(Bestand = MinBestand, 'Mindestbestand', 'Überstand')) AS Bestandsbewertung, Teile.*
FROM Teile
I tried this code but HSQL says it doesn't know IF.
This is what the Table looks like if it helps
It seems HSQL doesn't accept IF. After some trial and error I came to this solution to the problem.
SELECT Teile.*,
CASE Bestand WHEN < MinBestand THEN 'Mangel'
WHEN = MinBestand THEN 'Mindestbestand'
WHEN > MinBestand THEN 'Überfluß' END AS Bestandsbewertung
FROM Teile
It seems to work without any issues.

How to find two strings in a CLOB column?

Ive tried many queries to find... just one word and I can´t even make that.
Its a DB2 database Im using com.ibm.db2.jcc.DB2Driver
This brings me info:
select *
from JL_ENR
where id_ws = '002'
and dc_dy_bsn = '2014-08-25'
and ai_trn = 2331
the JL_TPE column is the CLOB column where I want to find two strings in that search result ( and dc_dy_bsn = '2014-08-25'
and ai_trn = 2331 ).
So first I tried with one:
select
dbms_lob.substr(clob_column,dbms_lob_instr(JL_TPE,'CEMENTO'),1)
from
JL_ENR
where
dbms_lob.instr(JL_TPE,'CEMENTO')>0;
didnt work
SELECT * FROM JL_ENR WHERE dbms_lob.instr(JL_TPE,'CEMENTO')>0
and ai_trn = 2331
and dc_dy_bsn = '2014-08-25'
didnt work
Select *
From JL_ENR
Where NOT
DBMS_LOB.INSTR(JL_TPE, 'CEMENTO', 1, 1) = 0;
didn´t work
Could someone explain me how to find two strings please?
Or a tutorial link where it is explained how to make it work...
Thanks.
Can you provide some sample data and the version you are using? Your example should work (tested on v10.5.0.1):
db2 "create table test ( x int, y clob(1M) )"
db2 "insert into test (x,y) values (1,cast('The string to find is CEMENTO, how do we do that?')"
db2 "insert into test (x,y) values (2,cast('The string to find is CEMENT, how do we do that?' as clob))"
db2 "select x, DBMS_LOB.INSTR(y, 'CEMENTO', 1) from test where DBMS_LOB.INSTR(y, 'CEMENTO', 1) > 0"
X 2
----------- -----------
1 23
1 record(s) selected.
I had to search for a specific value in the where clause. I used TEXTBLOB LIKE '%Search value%' and it worked! This was for db2 in a CLOB(536870912) column.

Hibernate createSQLQuery and Toad SQL query return different results - parameter problems?

I'm a newbie at Hibernate so excuse me if some of this is glaringly obvious but it's been a very, very long day. I am trying to create and execute a simple query in Hibernate and Toad/Oracle.
The Toad/Oracle sql reads:
select
count(*)
from
fpps_owner.fee_claim_payment_lines l,
fpps_owner.fee_claim_payments p
where
l.fee_claim_payment_id = p.fee_claim_payment_id and
p.claim_index = 87167895
The above returns 10 records, which is correct
The following Java code returns 0 records, which is NOT correct
String sLinesAvailable =
"select count(*) from " +
"fpps_owner.fee_claim_payment_lines l, fpps_owner.fee_claim_payments p " +
"where " +
"l.fee_claim_payment_id = p.fee_claim_payment_id and p.claim_index = :id";
Query qLinesAvailable = em.createNativeQuery(sLinesAvailable);
qLinesAvailable.setParameter("id", "87167895"); // fails
qLinesAvailable.setParameter("id", 87167895); // fails
List<Object> out = (List<Object>) qLinesAvailable.getResultList();
BigDecimal x = (BigDecimal) out.get(0);
Returns 0 records. Using .getSingleResult() also returns 0 records.
What am I missing here?
Any help would be GREATLY appreciated!
If you are not seeing any malformed query errors, it seems like the parameter is not binding correctly.
To debug, I'd print out that SQL statement the line after you set the parameter. This is the only way you can see the SQL after the parameter is set in order to compare it with Toad.
What does your binding file look like? Maybe you have a different name in there for the ID, so it's not able to find it based on the name. Trying binding with the parameter's order value, just as a test.
This might give some ideas: http://www.mkyong.com/hibernate/hibernate-parameter-binding-examples/
Best of luck! We've all been there :)
What happens when you try:
(Number) query.getSingleResult();
Your query isn't returning a list, but rather just a count.
Good luck.

What is the best way to run N independent column updates in PostgreSQL? What is the best way to do it in the SQL spec?

I'm looking for a more efficient way to run many columns updates on the same table like this:
UPDATE TABLE table
SET col = regexp_replace( col, 'foo', 'bar' )
WHERE regexp_match( col, 'foo' );
Such that foo, and bar, will be a combination of 40 different regex-replaces. I doubt even 25% of the dataset needs to be updated at all, but what I'm wanting to know is it is possible to cleanly achieve the following in SQL.
A single pass update
A single match of the regex, triggers a single replace
Not running all possible regexp_replaces if only one matches
Not updating all columns if only one needs the update
Not updating a row if no column has changed
I'm also curious, I know in MySQL (bear with me)
UPDATE foo SET bar = 'baz'
Has an implicit WHERE bar != 'baz' clause
However, in PostgreSQL I know this doesn't exist: I think I could at least answer one of my questions if I knew how to skip a single row's update if the target columns weren't updated.
Something like
UPDATE TABLE table
SET col = *temp_var* = regexp_replace( col, 'foo', 'bar' )
WHERE col != *temp_var*
Do it in code. Open up a cursor, then: grab a row, run it through the 40 regular expressions, and if it changed, save it back. Repeat until the cursor doesn't give you any more rows.
Whether you do it that way or come up with the magical SQL expression, it's still going to be a row scan of the entire table, but the code will be much simpler.
Experimental Results
In response to criticism, I ran an experiment. I inserted 10,000 lines from a documentation file into a table with a serial primary key and a varchar column. Then I tested two ways to do the update. Method 1:
in a transaction:
opened up a cursor (select for update)
while reading 100 rows from the cursor returns any rows:
for each row:
for each regular expression:
do the gsub on the text column
update the row
This takes 1.16 seconds with a locally connected database.
Then the "big replace," a single mega-regex update:
update foo set t =
regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(regexp_replace(t,
E'\bcommit\b', E'COMMIT'),
E'\b9acf10762b5f3d3b1b33ea07792a936a25e45010\b',
E'9ACF10762B5F3D3B1B33EA07792A936A25E45010'),
E'\bAuthor:\b', E'AUTHOR:'),
E'\bCarl\b', E'CARL'), E'\bWorth\b',
E'WORTH'), E'\b\b',
E''), E'\bDate:\b',
E'DATE:'), E'\bMon\b', E'MON'),
E'\bOct\b', E'OCT'), E'\b26\b',
E'26'), E'\b04:53:13\b', E'04:53:13'),
E'\b2009\b', E'2009'), E'\b-0700\b',
E'-0700'), E'\bUpdate\b', E'UPDATE'),
E'\bversion\b', E'VERSION'),
E'\bto\b', E'TO'), E'\b2.9.1\b',
E'2.9.1'), E'\bcommit\b', E'COMMIT'),
E'\b61c89e56f361fa860f18985137d6bf53f48c16ac\b',
E'61C89E56F361FA860F18985137D6BF53F48C16AC'),
E'\bAuthor:\b', E'AUTHOR:'),
E'\bCarl\b', E'CARL'), E'\bWorth\b',
E'WORTH'), E'\b\b',
E''), E'\bDate:\b',
E'DATE:'), E'\bMon\b', E'MON'),
E'\bOct\b', E'OCT'), E'\b26\b',
E'26'), E'\b04:51:58\b', E'04:51:58'),
E'\b2009\b', E'2009'), E'\b-0700\b',
E'-0700'), E'\bNEWS:\b', E'NEWS:'),
E'\bAdd\b', E'ADD'), E'\bnotes\b',
E'NOTES'), E'\bfor\b', E'FOR'),
E'\bthe\b', E'THE'), E'\b2.9.1\b',
E'2.9.1'), E'\brelease.\b',
E'RELEASE.'), E'\bThanks\b',
E'THANKS'), E'\bto\b', E'TO'),
E'\beveryone\b', E'EVERYONE'),
E'\bfor\b', E'FOR')
The mega-regex update takes 0.94 seconds to update.
At 0.94 seconds compared to 1.16, it's true that the mega-regex update is faster, running in 81% of the time of doing it in code. It is not, however a lot faster. And ye Gods, look at that update statement. Do you want to write that, or try to figure out what went wrong when Postgres complains that you dropped a parenthesis somewhere?
Code
The code used was:
def stupid_regex_replace
sql = Select.new
sql.select('id')
sql.select('t')
sql.for_update
sql.from(TABLE_NAME)
Cursor.new('foo', sql, {}, #db) do |cursor|
until (rows = cursor.fetch(100)).empty?
for row in rows
for regex, replacement in regexes
row['t'] = row['t'].gsub(regex, replacement)
end
end
sql = Update.new(TABLE_NAME, #db)
sql.set('t', row['t'])
sql.where(['id = %s', row['id']])
sql.exec
end
end
end
I generated the regular expressions dynamically by taking words from the file; for each word "foo", its regular expression was "\bfoo\b" and its replacement string was "FOO" (the word uppercased). I used words from the file to make sure that replacements did happen. I made the test program spit out the regex's so you can see them. Each pair is a regex and the corresponding replacement string:
[[/\bcommit\b/, "COMMIT"],
[/\b9acf10762b5f3d3b1b33ea07792a936a25e45010\b/,
"9ACF10762B5F3D3B1B33EA07792A936A25E45010"],
[/\bAuthor:\b/, "AUTHOR:"],
[/\bCarl\b/, "CARL"],
[/\bWorth\b/, "WORTH"],
[/\b<cworth#cworth.org>\b/, "<CWORTH#CWORTH.ORG>"],
[/\bDate:\b/, "DATE:"],
[/\bMon\b/, "MON"],
[/\bOct\b/, "OCT"],
[/\b26\b/, "26"],
[/\b04:53:13\b/, "04:53:13"],
[/\b2009\b/, "2009"],
[/\b-0700\b/, "-0700"],
[/\bUpdate\b/, "UPDATE"],
[/\bversion\b/, "VERSION"],
[/\bto\b/, "TO"],
[/\b2.9.1\b/, "2.9.1"],
[/\bcommit\b/, "COMMIT"],
[/\b61c89e56f361fa860f18985137d6bf53f48c16ac\b/,
"61C89E56F361FA860F18985137D6BF53F48C16AC"],
[/\bAuthor:\b/, "AUTHOR:"],
[/\bCarl\b/, "CARL"],
[/\bWorth\b/, "WORTH"],
[/\b<cworth#cworth.org>\b/, "<CWORTH#CWORTH.ORG>"],
[/\bDate:\b/, "DATE:"],
[/\bMon\b/, "MON"],
[/\bOct\b/, "OCT"],
[/\b26\b/, "26"],
[/\b04:51:58\b/, "04:51:58"],
[/\b2009\b/, "2009"],
[/\b-0700\b/, "-0700"],
[/\bNEWS:\b/, "NEWS:"],
[/\bAdd\b/, "ADD"],
[/\bnotes\b/, "NOTES"],
[/\bfor\b/, "FOR"],
[/\bthe\b/, "THE"],
[/\b2.9.1\b/, "2.9.1"],
[/\brelease.\b/, "RELEASE."],
[/\bThanks\b/, "THANKS"],
[/\bto\b/, "TO"],
[/\beveryone\b/, "EVERYONE"],
[/\bfor\b/, "FOR"]]
If this were a hand-generated list of regex's, and not automatically generated, my question is still appropriate: Which would you rather have to create or maintain?
For the skip update, look at suppress_redundant_updates - see http://www.postgresql.org/docs/8.4/static/functions-trigger.html.
This is not necessarily a win - but it might well be in your case.
Or perhaps you can just add that implicit check as an explicit one?