The database I'm working on has a field in one table as a text whereas the other table has the field in a number format. I cannot change the field format at all in the database. Therefore I need to know how to convert the field from text to number before linking (or join) the tables to pull the data.
SELECT DISTINCT tblCoachingDB.ID, tblCoachingDB.SourceId, tblCoachingDBSource.ID
FROM tblCoachingDB, tblCoachingDBSource
WHERE (((tblCoachingDB.SourceId)="12"));
The tblCoachingDB.SourceID is a TEXT whereas the tblCoachingDBSource.ID is a NUMBER
You can use CStr() to cast a number as text and JOIN that to another text field.
SELECT DISTINCT
tblCoachingDB.ID,
tblCoachingDB.SourceId,
tblCoachingDBSource.ID
FROM
tblCoachingDB INNER JOIN tblCoachingDBSource
ON tblCoachingDB.SourceId = CStr(tblCoachingDBSource.ID)
WHERE tblCoachingDB.SourceId='12';
Actually I would leave out the WHERE clause until after you confirm the JOIN works properly.
You originally asked to JOIN by converting the text field to number. I first suggested text instead because I recall Access was less likely to object. But my memory about that is shaky, and if you want numeric for both sides of the JOIN, see which of these (if any) works best for you:
ON Int(tblCoachingDB.SourceId) = tblCoachingDBSource.ID
ON CLng(tblCoachingDB.SourceId) = tblCoachingDBSource.ID
ON Val(tblCoachingDB.SourceId) = tblCoachingDBSource.ID
Note I offered this suggestion only because you told us you are not permitted to alter your tblCoachingDB table's design to make SourceId numeric instead of text datatype. Since you can't make that change, you will have to live with the run-time performance impact of converting the datatype of a JOIN field. That is not a good thing, but I don't know how bad it will be. Good luck.
Assuming that all values in tblCoachingDB.SourceID are numbers, you could create a query, selecting all fields from tblCoachingDB EXCEPT SourceID. Then add a new field to the query SourceID: clng(tblCoachingDB.SourceID)
You would then use the query instead of tblCoachingDB anywhere you needed to make the join. A second alternative would be to create a query for tblCoachingDBSource and using SourceID: cstr(tblCoaching.SourceID) A third alternative would be:
SELECT * FROM tblCoachingDB, tblCoachingDBSource
WHERE (clng(tblCoachingDB.SourceId)=tblCoachingDBSource.ID
AND ((tblCoachingDB.SourceId)="12"));
Related
I'm trying to get results when both tables have the same machine number and there are entries that have the same number in both tables.
Here is what I've tried:
SELECT fehler.*,
'maschine.Maschinen-Typ',
maschine.Auftragsnummer,
maschine.Kunde,
maschine.Liefertermin_Soll
FROM fehler
JOIN maschine
ON ltrim(rtrim('maschine.Maschinen-Nr')) = ltrim(rtrim(fehler.Maschinen_Nr))
The field I'm joining on is a varchar in both cases. I tried without trims but still returns empty
I'm using MariaDB (if that's important).
ON ltrim(rtrim('maschine.Maschinen-Nr')) = ltrim(rtrim(fehler.Maschinen_Nr)) seems wrong...
Is fehler.Maschinen_Nr really the string 'maschine.Maschinen-Nr'?
SELECT fehler.*, `maschine.Maschinen-Typ`, maschine.Auftragsnummer, maschine.Kunde, maschine.Liefertermin_Soll
FROM fehler
JOIN maschine
ON ltrim(rtrim(`maschine.Maschinen-Nr`)) = ltrim(rtrim(`fehler.Maschinen_Nr`))
Last line compared a string to a number. This should be doing it.
Also, use the backtick to reference the column names.
The single quotes are string delimiters. You are comparing fehler.Maschinen_Nr with the string 'maschine.Maschinen-Nr'. In standard SQL you would use double quotes for names (and I think MariaDB allows this, too, certain settings provided). In MariaDB the commonly used name qualifier is the backtick:
SELECT fehler.*,
`maschine.Maschinen-Typ`,
maschine.Auftragsnummer,
maschine.Kunde,
maschine.Liefertermin_Soll
FROM fehler
JOIN maschine
ON trim(`maschine.Maschinen-Nr`) = trim(fehler.Maschinen_Nr)
(It would be better of course not to use names with a minus sign or other characters that force you to use name delimiters in the first place.)
As you see, you can use TRIM instead of LTRIM and RTRIM. It would be better, though, not to allow space at the beginning or end when inserting data. Then you wouldn't have to remove them in every query.
Moreover, it seems Maschinen_Nr should be primary key for the table maschine and naturally a foreign key then in table fehler. That would make sure fehler doesn't contain any Maschinen_Nr that not exists exactly so in maschine.
To avoid this problems in future, the convention for DB's is snake case(lowercase_lowercase).
Besides that, posting your DB schema would be really helpfull since i dont guess your data structures.
(For friendly development, is usefull that variables, tables and columns should be written in english)
So with this, what is the error that you get, because if table "maschine" has a column named "Maschinen-Nr" and table "fehler" has a column named "Maschinen_Nr" and the fields match each other, it should be correct
be careful with Maschinen-Nr and Maschinen_Nr. they have - and _ on purpose?
a very blind solution because you dont really tell what is your problem or even your schema is:
SELECT table1Alias.*, table2Alias.column_name, table2Alias.column_name
FROM table1 [table1Alias]
JOIN table2 [table2Alias]
ON ltrim(rtrim(table1Alias.matching_column)) = ltrim(rtrim(table2Alias.matching_column))
where matching_columns are respectively PK and FK or if the data matches both columns [] are optional and if not given, will be consider table_name
I'm trying to ascertain the best way to test for blank/empty/null text records.
By this I mean text records which are either:
Null
An Empty String ("")
Any number of spaces (e.g. " ")
I've experimented with varying query criteria using the following table (named Table1):
Here, the Spaces record contains an arbitrary number number of spaces, the Empty String record contains an empty string (""), and the Null record is just that.
My first thought to achieve my goal was to use a query such as:
SELECT * FROM Table1 WHERE TextField IS NULL OR Trim(TextField)=""
And this indeed returns the three target records: Spaces, Empty String & Null.
However somewhat oddly, using:
SELECT * FROM Table1 WHERE TextField = ""
Returns both the Empty String record and the Spaces record:
Which leads me to think that my query can omit the Trim function and become:
SELECT * FROM Table1 WHERE TextField IS NULL OR TextField=""
But is this reliable?
Is this best practice when selecting empty text records?
Alternatively I considered using:
SELECT * FROM Table1 WHERE Nz(TextField)=""
Are there drawbacks to this approach?
Are there better ways to achieve this?
EDIT: To be specific, my question is ultimately:
What is the best way to select blank text records?
For normal text, Access handles strings with only spaces as empty strings (e.g. SELECT " " = "" returns -1 = True).
This means that the solution introduced by June7, WHERE TextField & "" = "", is likely the most efficient solution. Another contender is the Nz function, which is handled by the database engine and somewhat optimized.
When using indexes, however, both string concatenation and function calls invalidate the index. WHERE TextField IS NULL OR TextField="" doesn't, and will be the fastest by far if TextField is indexed.
If you bring rich text into the mix, you're not going to get away with anything but casting it to normal text first. In Access 2016, when you enter a space in a rich text field, it actually contains the following: <div> </div> (you can see this by using RichTextField & "").
For a rich text field, indexes are not going to work anyway, so you can use the following:
WHERE PlainText(RichTextField) & "" = ""
Nz(TextField)=""
Is the approach most often used when dealing with nulls and empty strings.
In Access, The Long Text data type will automatically be trimmed to save space, this is why Trim(TextField) is the same as TextField. If you ever convert it to a Rich Text data type, these will be different. In that case:
TRIM(Nz(TextField))=""
Should cover all your bases.
I have a simple scenario as follow:
I have 2 column : 1) id and 2) text(which is long text format)
I use the simple query to extract all info from mysql as follow:
select id,text from dbtest
but the problem is for different id I might have the same text but in retrieval time I do not want to return rows with the same text again and again so I do not want to return the repeated texts,I tried to use distinct but it was not working,
How can I do that , any idea?
One option is to use user-defined variables:
select id,
#text:=if(#text=text, '', text) text
from dbtest, (select #text:='') t
order by text
SQL fiddle demo
I would generally recommend doing this on the application side rather than the database though.
Distinct works on all selected columns. You must use a GROUP BY:
SELECT id,text FROM dbtest GROUP BY text
So I have two questions, can you post the code you are using for us? And are some of the fields for the text empty?
The query might be detecting a "Null" kind of event in which if the field is empty, it repeats the last one because the variable might not be getting unset. In which case you might just want to unset your variables at the end of your (I'm assuming) while loop.
To order by name I'm using 'order by name'
But the names contain double colons : '::'
How can I order by the text that occurs subsequent to the double colons ?
So :
aaaa::bbbb
aaaa::aaaa
aaaa::1234
aaaa::a1234
Will be ordered :
aaaa::1234
aaaa::aaaa
aaaa::a1234
aaaa::bbbb
Order by the substring ans use locate to find where it starts:
order by substring(name, locate('::', name) + 3, 30)
It'll decrease performance since no index will be used.
You would have to create a new field in MySQL then insert the second part of your text into it. Sort by uses various indexes and algorithms (such as divide and conquer).
As such it would not work on sorting on a specific portion of a specific string, and if you did manage to 'fake' a way of doing it, the performance would be terrible due to lack of indexes.
Sorry, I realise this probably isn't the answer your looking for, but I'm afraid the best way is the slightly longer way, but at least you can then do it at lighting fast speeds if you add an index to it :)
You must split the text into two columns and order by the latter one. You can either split and join the columns in application code or use views and stored procedures to make it look like one column to a database client.
about your sorting , according to ascii values numbers come first before alphabets,
so aaaa:1234 should come first
You can retrieve the values and sort in PHP
Navsort
<?php
$arr = array("aaaa::bbbb","aaaa::aaaa","aaaa::1234","aaaa::a1234");
$sec=$arr;
natsort($sec);
print_r ($sec);
?>
You may try the following approach
Get all records where All data is Alphabet after ::
UNION
Get all records where All data is Numeric after ::
I've to ask your help to solve this problem.
My website has a search field, let's say user writes in "Korg X 50"
In my database in table "products" i have a filed "name" that holds "X50" and a field "brand" that hold "Korg". Is there a way to use the UNION option to get the correct record ?
And if the user enters "Korg X-50" ?
Thank you very much !
Matteo
May be you should use full-text search
SELECT brand, name, MATCH (brand,name) AGAINST ('Korg X 50') AS score
FROM products WHERE MATCH (brand,name) AGAINST ('Korg X 50')
As far as I understand you don't need UNION but something like
SELECT * FROM table1
WHERE CONCAT(field1, field2) LIKE '%your_string%'
On client side you get rid of all characters (like space, hyphen, etc) in your_string that appears in user input and cannot be in field1 or field2.
So, user input Korg X 50 as well as Korg X-50 becomes KorgX50.
you will need to get some form of searchable text.
either parse out the input for multiple key words and match each separately, or perhaps try to append them all together and match to the columns appended in the same way.
you will also need either a regex, or maybe a simpler search and replace to get rid of spaces and dashes after the append before the comparison.
in general, allowing users to search for open ended text strings is more complicated than 'what union do i use'... you will ideally also be worried about slight misspellings and capitalization, and keyword order.
you may consider pulling all keywords out from your normal record into a separate keyword list associated with each product, then use that list to perform your searches.
If you do not want to parse user input and use as it is, then you will need to use a query like this
select * from products where concat_ws(' ',brand,name) = user_input -- or
select * from products where concat_ws(' ',brand,name) like %user_input%
However, this query won't return result if user enters name "Korg X-50" and your table contains "Korg" and "X50", then you need to do some other thing to achive this. You may look at http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_soundex however it won't be a complete solution. Look for text indexing libraries for that ex: lucene