I want to add a BINARY(35) column to a table in which values are written whose bits are each assigned to a specific meaning.
i.e. "000110001010..."
1st bit: day 1,
2nd bit: day 2,
etc..
I've found out how to write the value into the table
INSERT INTO MYTABLE VALUES(x'03011...');
but how do I retrieve it from the database?
If I cast the column as a character string, I'll loose everything past the first x'00' (NULL) in the value. In my application, its entirely possible that they'll still be '1's past this.
Because I'm using the C++ connector, I've only its API functions to retrieve the data so I'll need to know the type of the data retrieved. The API does not have a getBinary() function. If any of you can tell me which function to use, I'd really appreciate it.
Got the answer from another Q&A site.
SELECT HEX(mycolumn) FROM MYTABLE;
If anyone wants to read more about this:
Hexidecimal Literals: https://dev.mysql.com/doc/refman/5.7/en/hexadecimal-literals.html
Bit-Field Literals: https://dev.mysql.com/doc/refman/5.7/en/bit-field-literals.html
Substring(cast column as varchar), 1,1)
Related
I have several things which I want to discuss with you guys.
Since, they were just simple questions, so no dataset here.
Suppose I have a datetime type column which called started_date, the value in it was like:
yyyy-mm-dd hh:mm:ss. So, if I want to select some IDs which were larger than one specified day (let's say June/01/2017), can I just using
select ID, started_date
from table1
where started_date>"2017-06-01";
Does this work?
I tried some samples, and it worked indeed in the mysql. However, someone told me that I cannot compare the datetime column with string values without converting their format. And it confused me. Because I thought the value "2017-06-01" here was date type value, so it does not need convert. Or am I thinking wrong?
Another thing was about the double quote and single quote, I understand that the single quote was used for string values. However, in this case, when I used double quote to quote "2017-06-01", it works. So, does it mean the double quote can quote date values?
I am just asking, so any response is welcome.
Thanks.
Your query is fine. You are using a safe date/time format for the string. In other words, if you have to store the value as a string, then use that format.
I would write the code as:
where started_date >= '2017-06-01'
I see no reason to exclude midnight on 2017-06-01 (although you might have a reason). Second, single quotes are the standard delimiter for strings.
That said, you can store the value as a string.
As a best practice, I stay away from comparing time-stamps to date-stamps. In this case you can be explicit and truncate the start date. And yes, use single quotes instead.
where SUBSTR(started_date, 1, 10) > '2017-06-01'
To make sure it works you could just convert the date time to a string first and compare the two strings:
to_char(started_date,'YYYY-MM-DD') >= '2017-06-01'
The Strings will compare just fine in that format.
I've a table on ArcGis which contains nummbers and dates. I need to filter these via a sql-query. I just have the possibility to change the where clause.
See here: https://services3.arcgis.com/rKOPqLnqVBkPP9th/arcgis/rest/services/Arbeitsmappe1/FeatureServer/0//query
Just type in the where clause 1=1 and outfield * then you will get all results.
I have to filter installierte_leistung which contains numbers in the following formats:
1.050,20 ; 18; 0,1 ; 1.230
and dates of following format: 11.04.08
wished filters:
installierte_leistung: I want to execute a sql-statement like: where (installierte_leistung BETWEEN '1' AND '2'). In the result there is also the 18. Or if I ask for values greater 10 it shows me also the 1.050,20.
I tried to convert with cast and convert to decimal, signed, unsigned, integer and so on, but the query has been always invalid. I tried with 'number' and with number and with "number". lowercase and uppercase and almost all thinkable possibilities. I get no results with cast or convert.
Same issue with the Date. I want to filter monthly. so means between 01.2008 and 09.2009 for instance.
Could someone please help me? Thanks a lot!
Falk
I had a similar problem in the past with nested query. The more database specific queries (like cast and so) don't work because ArcGIS server is by default configured to work only with standardized queries. If you need to use more specific queries you have to change "standardizedQueries": "false" in server setting, check here how (bottom of the page): http://resources.arcgis.com/en/help/main/10.2/index.html#//015400000641000000. Should work for you. Good luck.
I ran into a problem with SQL Server Integration Services 2012's new string function in the Expression Editor called TOKEN().
This is supposed to help you parse a delimited record. If the record comes out of a flat file, you can do this with the Flat File Source. In this case, I am dealing with old delimited import records that were stored as strings in a database VARCHAR field. Now they need to be extracted, massaged, and re-exported as delimited strings. For example:
1^Apple^0001^01/01/2010^Anteater^A1
2^Banana^0002^03/15/2010^Bear^B2
3^Cranberry^0003^4/15/2010^Crow^C3
If these strings are in a column called OldImportRecord, the delimiter is a caret (as shown), and we wish to put the fifth field into a Derived Column, we would use an expression like:
TOKEN(OldImportRecord,"^",5)
This returns Anteater, Bear, Crow, etc. In fact, we can create Derived Columns for each of the fields in this record (note that the index is one-based), change them as needed, and then build another delimited record for export.
Here's the problem. What if some of our data includes some empty strings (or Nulls rendered as empty strings)?
4^^0004^6/15/2010^Duck^D4
The TOKEN() fails to count the adjacent column delimiters, which throws off the column count. Now it only sees five columns instead of six columns. Our TOKEN(OldImportRecord,"^",5) returns "D4" instead of the intended "Duck". When we extract the fourth column, we wind up trying to put "Duck" into a Date column, and all sorts of fun ensues.
Here's a partial workaround:
TOKEN(REPLACE(OldImportRecord,"^^","^ ^"),"^",5)
Notice this misses every second delimiter pair, so it will fail for a string like "5^^^^Emu^E5", which looks like"5^ ^^ ^Emu^E5" after the REPLACE(). The column count is still wrong.
So here's my full workaround. This includes two nested REPLACE statements(), an RTRIM() to remove the superfluous spaces, and a DT_STR cast because I would like to keep the result in VARCHAR:
(DT_STR,255,1252)RTRIM(TOKEN(REPLACE(REPLACE(OldImportRecord,"^^","^ ^"),"^^","^ ^"),"^",5))
I am posting this for information, since others may also run into this problem.
Does anyone have a better workaround, or even a real solution?
Reason for the issue:
TOKEN method in SSIS uses the implementation of strtok function in C++. I gathered this information while reading the book Microsoft® SQL Server® 2012 Integration Services. It is mentioned as note on page 113 (I like this book! Lots of nice information.).
I searched for the implementation of strtok function and I found the following links.
INFO: strtok(): C Function -- Documentation Supplement - The code sample in this link shows that the function does ignore consecutive delimiter characters.
The answers to the following SO questions point out that strtok function is designed to ignore consecutive delimiters.
Need to know when no data appears between two token separators using strtok()
strtok_s behaviour with consecutive delimiters
I think that the TOKEN and TOKENCOUNT functions are working as per design but whether that is how SSIS should behave might be a question for the Microsoft SSIS team.
Original Post - Above section is an update:
I created a simple package in SSIS 2012 based on your data inputs. As you had described in your question, the TOKEN function does not behave as intended. I agree with you that the function doesn't seem to work. This post is not an answer to your original issue.
Here is an alternative way to write the expression in a relatively simpler fashion. This will only work if the last segment in your input record will always have a value (say A1, B2, C3 etc.).
Expression can be rewritten as:
This statement will take the input record as the parameter, the delimiter caret (^) as the second parameter. The third parameter calculates the total number segments in the records when split by the delimiter. If you have data in the last segment, you are guaranteed to have two segments. You can then subtract 1 to fetch the penultimate segment.
(DT_STR,50,1252)TOKEN(OldImportRecord,"^",TOKENCOUNT(OldImportRecord,"^") - 1)
I created a simple package with data flow task. OLE DB source retrieves the data and the derived transformation parses and splits the data as per the screenshot below. The output is then inserted into the destination table. You can see the source and destination tables in the last screenshot. Destination table has two columns. The first column stores the penultimate segment data and the segments count based on the delimiter (which again isn't correct). You can notice that the last record didn't fetch the correct results. If the last record didn't have the value 8, then the above expression will fail because the expression will evaluate to zero index.
Hope that helps to simplify your expression.
If you don't hear from anyone else, I would recommend logging this issue in Microsoft Connect website.
Create table and populate scripts:
CREATE TABLE [dbo].[SourceTable](
[OldImportRecord] [varchar](50) NOT NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[DestinationTable](
[NewImportRecord] [varchar](50) NOT NULL,
[CaretCount] [int] NOT NULL
) ON [PRIMARY]
GO
INSERT INTO dbo.SourceTable (OldImportRecord) VALUES
('1^Apple^0001^01/01/2010^Anteater^A1'),
('2^Banana^0002^03/15/2010^Bear^B2'),
('3^Cranberry^0003^4/15/2010^Crow^C3'),
('4^^0004^6/15/2010^Duck^D4'),
('5^^^^Emu^E5'),
('6^^^^Geese^F6'),
('^^^^Pheasant^G7'),
('8^^^^Sparrow^');
GO
Derived column transformation inside data flow task:
Data in source and destination tables:
Not only does TOKEN skip adjacent delimiters, it also skips leading and trailing delimiters as well. So, using your example, if you had a field "good" field that looks like this:
1^Apple^0001^01/01/2010^Anteater^A1
Followed by one with adjacent and leading delimiters like this:
^^^0004^6/15/2010^Duck^
TOKENCOUNT would only find two delimiters and you'd end up with 0004 assigned to Token1, 6/15/2010 for Token2, and Duck for Token3.
I used a different kind of replace. Rather than placing spaces between adjacent delimiters, which wouldn't help with leading or training, I used replace to surround the delimiters with characters I absolutely wouldn't find in my text. The following Expression works well for me. It's wordy, but it is what it is.
(DT_STR,255,1252)REPLACE(TOKEN(REPLACE(OldImportRecord,"^","~^~"),"^",1),"~","")
Of course, you'd replace the number 1 with whatever Token you wanted and adjust the cast according to your needs. Hope that helps.
Is it possible to find the min value of a column of floating numbers using a mysql function? Suppose I have the following table:
id | value a | 24.88 a | 119.99
If I try:
SELECT MIN(value) FROM [table name] GROUP BY id;
mysql returns:
119.99
After testing this with different floating numbers I believe that this is the case because mysql takes the first character in each of the strings "1" and "2" and then selects a min based on which character is smaller.
I've read through this forum and others trying to find an answer but it seems nobody has raised this problem.
I should mention I've also tried CEIL(value) but that function also seems to have some bugs and I'd prefer to keep the number a floating number and not an integer.
Thanks everyone.
It looks like the column is being stored as a character-based data type. You can solve this in one of two ways:
Change the column type to a numeric type
change the query to add CAST around the value: MIN(CAST(value AS DECIMAL))
The column change might look like this:
ALTER TABLE my_table MODIFY COLUMN value double;
And, as far as I know, MySQL will attempt to convert the data for you. See the note here, which states it "tries".
In a MySQL database, I have a table which contains itemID, itemName and some other fields.
Sample records (respectively itemID and itemName):
vaX652bp_X987_foobar, FooBarItem
X34_bar, BarItem
tooX56, TOOX_What
I want to write a query which gives me an output like:
652, FooBarItem
34, BarItem
56, TOOX_What
In other words, I want to extract out the number from the itemID column. But the condition is that the extracted number should be the number that occurs after the first occurence of the character "X" in the itemID column.
I am currently trying out locate() and substring() but could not (yet) achieve what I want..
EDIT:
Unrelated to the question - Can any one see all the answers (currently two) to this question ? I see only the first answer by "soulmerge". Any ideas why ? And the million dollar question - Did I just find a bug ?!
That's a horrible thing to do in mysql, since it does not support extraction of regex matches. I would rather recommend pulling the data into your language of choice and processing it there. If you really must do this in mysql, using unreadable combinations of LOCATE and SUBSTRING with multiple CASEs is the only thing I can think of.
Why don't you try to make a third column where you can store, at the moment of the insertion of the record (separating the number in PHP or so), the number alone. So this way you use a little more of space to save a lot of processing.
Table:
vaX652bp_X987_foobar, 652, FooBarItem
X34_bar, 34, BarItem
tooX56, 56, TOOX_What
This isn't so unreadable :
SELECT 0+SUBSTRING(itemID, LOCATE("X", itemID)+1), itemName FROM tableName