Constructing a SQL Server query for the first time today, and was surprised to see that this alias didn't work:
SELECT
INVOICE_INVOICE_NUMBER AS invno,
INVOICE_INVOICE_SEQ AS lineno
FROM
INVOICED
But this did:
SELECT
INVOICE_INVOICE_NUMBER AS invoice,
INVOICE_INVOICE_SEQ AS line
FROM
INVOICED
Changing the alias name is no big deal - but it would be good to know why this particular alias didn't work and how I can prevent or be aware of any future keywords to avoid.
LineNo is a reserved word. You can encase it in brackets to use it.
SELECT INVOICE_INVOICE_SEQ AS [lineno]
Reserved words
The answer is in your question itself. Keywords change colour and you should be able to easily make that out, unless you are typing your SQL query in notepad. Ideally it is not a good practice to use keywords for aliases, but if you have to, wrap them in square brackets - [ ].
Typically, reserved words turn blue, functions turn pink and system objects turn green. Of course you do have the ability to change the font in SSMS (Options > Environment > Fonts and Colors)
Raj
Related
Can I have whitespace in a column name that I use in a dataset inside of Report Builder? E. g. from a query like
SELECT col as [red cards] FROM table
I get an error similar to (due to translation)
<Name>
Please enter a valid name. The name cannot contain any spaces...
Here it is suggested to use underscores instead, but google shows precious little on the topic.
I am using the query somewhere else as well, so an as-descriptive-and-readable-as-possible name would be more desirable.
What you have should work (I've just tested this it worked for me) with something this simple. I have sometimes had issues with the use of alias in queries which have multiple joins.
If it still doesn't want to work, try RedCards or Red_Cards.
I want to find out using a select statement what columns in a table share similar information.
Example: Classes table with ClassID, ClassName, ClassCode, ClassDescription columns.
This was part of my SQL class that I already turned in. The question asked "What classes are part of the English department?"
I used this Select statement:
SELECT *
FROM Classes
WHERE ClassName LIKE "English%" OR ClassCode LIKE "ENG%"
Granted we have only input one actual English course in this database, the end result was it executed fine and displayed everything for just the English class. Which I thought was a success since we did populate other non English courses in the database.
Anyways, I was told I should have used a BETWEEN statement.
I am just sitting here thinking they would both do what I needed them to do right?
I'm using SQL Server 2014
No, BETWEEN would probably be a bad idea here. BETWEEN doesn't allow wildcards and doesn't do any pattern matching in any RDBMS I've used. So you'd have to say BETWEEN 'ENG' AND 'English'. Except that doesn't return things like 'English I' (which would be after 'English' in a sorted list).
It would also potentially include something like 'Engineering' or 'Engaging Artistry', but that's a weakness of your existing query, too, since LIKE 'ENG%' matches those.
If you happen to be using a case-sensitive collation you add a whole new dimension of complexity. Your BETWEEN statement gets even more confusing. Just know that capital letters generally come before lower case letters, so 'ENGRAVING I' would be included but 'Engraving I' would not. Additionally, 'eng' would not be included. Note that case-insensitive collation is the default.
Also whats the difference when searching for null values in one table
and one column
column_name =''
or
column_name IS NULL
You're not understanding the difference between an empty string and null.
An empty string is explicit. It says "This field has a known value and it is a string of zero length."
A null string is imprecise. It means "unknown". It could mean "This value wasn't asked for," or "This value was not available," or "This value has not yet been determined," or "This values does not make sense for this record."
"What is this person's middle name?"
"He doesn't have one. See, his birth certificate has no middle name listed." --> Empty string
"I don't know. He never told me and I don't have any birth or identity record." --> NULL
Note that Oracle, due to backwards compatibility, treats empty strings as NULLs. This is explicitly against ANSI SQL, but since Oracle is that old and that's how it's always worked that's how it will continue to work.
Another way to look at it is the example I tend to use with numbers. The difference between 0 and NULL is the difference between having a bank account with $0 balance and not having a bank account at all.
Nothing can be said unless we see table and its data.Though don't use between.
Secondly first find which of the column is not null by design.Say for example ClassName cannot be null then there is no use using ClassCode LIKE "ENG%",just ClassName LIKE "English%" is enough,similarly vice versa is also true.
Thirdly you should use same parameter in both column.for example
ClassName LIKE "English%" OR ClassCode LIKE "English%"
see the difference.
Select * FROM Classes
Where ClassName LIKE "%English%"
I was not able to solve this by myself so I hope I didn't miss any similar post here and I'm not wasting your time.
What I want is to identify (get a list) of all strings used in SQL Server code.
Example:
select 'WordToCatch1' as 'Column1'
from Table1
where Column2 = 'WordToCatch2'
If you put above code to SSMS all three words in apostrophes will be red but only words 'WordToCatch1' and 'WordToCatch2' are "real" strings used in code.
My goal is to find all those "real" strings in any code.
For example if I will have stored procedure 10k rows long it would be impossible to search them manually so I want something what will find all those "real" strings for me and return a list of them or something.
Thanks in advance!
The trouble is, Column1 is nothing particular different compared to WordToCatch1 and WordToCatch2 - not unless you parse the SQL yourself. You could modify your query to take the quotes away from Column1 and it will show up coloured black.
I guess a simple regex will show up all identifiers after an AS keyword, which would be easier than fully parsing SQL, if all the unwanted strings are like that, and its not just an example.
I remember when I was working with PHP several years back I could blow up my application by naming a MySQL column 'desc' or any other term that was used as an operator.
So, in general are there names I should avoid giving my table columns?
As long as you surround every column name with '[' and ']', it really doesn't matter what you use. Even a space works (try it: [ ]).
Edit: If you can't use '[' and ']' in every case, check the documentation for characters that are not allowable as well as keywords that are intrinsic to the system; those would be out of bounds. Off the top of my head, the characters allowed (for SqlServer) for an identifier are: a-z, A-Z, 0-9, _, $, #.
in general don't start with a number, don't use spaces, don't use reserved words and don't use non alphanumeric characters
however if you really want to you can still do it but you need to surround it with brackets
this will fail
create table 1abc (id int)
this will not fail
create table [1abc] (id int)
but now you need to use [] all the time, I would avoid names as the ones I mentioned above
Check the list of reserved keywords as indicated in other answers.
Also avoid using the "quoting" using quotes or square brackets for the sake of having a space or other special character in the object name. The reason is that when quoted the object name becomes case sensitive in some database engines (not sure about MSSQL though)
Some teams use the prefix for database objects (tables, views, columns) like T_PERSON, V_PERSON, C_NAME etc. I personally do not like this convention, but it does help avoiding keyword issues.
You should avoid any reserved SQL keywords (ex. SELECT) and from a best practices should avoid spaces.
Yes, and no.
Yes, because it's annoying and confusing to have names that match keywords, and that you have to escape in funny ways (when you're not consistently escaping)
and No, because it's possible to have any sequence of characters as an identifier, if you escape it properly :)
Use [square brackets] or "double quotes" to escape multi-word identifiers or keywords, or even names that have backslashes or any other slightly odd character, if you must.
Strictly speaking, there's nothing you can't name your columns. However, it will make your life easier if you avoid names with spaces, SQL reserved words, and reserved words in the language you're programming in.
You can use pretty much anything as long as you surround it with square brackets:
SELECT [value], [select], [insert] FROM SomeTable
I however like to avoid doing this, partly because typing square brackets everywhere is anoying and partyly because I dont generally find that column names like 'value' particularly descriptive! :-)
Just stay away from SQL keywords and anything which contains something other than letters and you shouldn't need to use those pesky square brackets.
You can surround a word in square brackets [] and basically use anything you'd like.
I prefer not to use the brackets, and in order to do so you just have to avoid reserved words.
MS SQL Server 2008 has these reserved words
Beware of using square brackets on updates, I had a problem using the following query:
UPDATE logs SET locked=1 WHERE [id] IN (SELECT [id] FROM ids)
This caused all records to be updated, however, this appears to work fine:
UPDATE logs SET locked=1 WHERE id IN (SELECT [id] FROM ids)
Note that this problem appears specific to updates, as the following returns only the rows expected (not all rows):
SELECT * FROM logs WHERE [id] IN (SELECT [id] FROM ids)
This was using MSDE 2000 SP3 and connecting to the database using MS SQL (2000) Query Analyzer V 8.00.194
Very odd, possibly related to this Knowledgebase bug http://support.microsoft.com/kb/140215
In the end I just removed all the unnecessary square brackets.
We're using SQL Server 2005 in a project. The users of the system have the ability to search some objects by using 'keywords'. The way we implement this is by creating a full-text catalog for the significant columns in each table that may contain these 'keywords' and then using CONTAINS to search for the keywords the user inputs in the search box in that index.
So, for example, let say you have the Movie object, and you want to let the user search for keywords in the title and body of the article, then we'd index both the Title and Plot column, and then do something like:
SELECT * FROM Movies WHERE CONTAINS(Title, keywords) OR CONTAINS(Plot, keywords)
(It's actually a bit more advanced than that, but nothing terribly complex)
Some users are adding numbers to their search, so for example they want to find 'Terminator 2'. The problem here is that, as far as I know, by default SQL Server won't index short words, thus doing a search like this:
SELECT * FROM Movies WHERE CONTAINS(Title, '"Terminator 2"')
is actually equivalent to doing this:
SELECT * FROM Movies WHERE CONTAINS(Title, '"Terminator"') <-- notice the missing '2'
and we are getting a plethora of spurious results.
Is there a way to force SQL Server to index small words? Preferably, I'd rather index only numbers like 1, 2, 21, etc. I don't know where to define the indexing criteria, or even if it's possible to be as specific as that.
Well, I did that, removed the "noise-words" from the list, and now the behaviour is a bit different, but still not what you'd expect.
A search won't for "Terminator 2" (I'm just making this up, my employer might not be really happy if I disclose what we are doing... anyway, the terms are a bit different but the principle the same), I don't get anything, but I know there are objects containing the two words.
Maybe I'm doing something wrong? I removed all numbers 1 ... 9 from my noise configuration for ENG, ENU and NEU (neutral), regenerated the indexes, and tried the search.
These "small words" are considered "noise words" by the full text index. You can customize the list of noise words. This blog post provides more details. You need to repopulate your full text index when you change the noise words file.
I knew about the noise words file, but I'm not why your "Terminator 2" example is still giving you issues. You might want to try asking this on the MSDN Database Engine forum where people that specialize in this sort of thing hang out.
You can combine CONTAINS (or CONTAINSTABLE) with simple where conditions:
SELECT * FROM Movies WHERE CONTAINS(Title, '"Terminator 2"') and Title like '%Terminator 2%'
While the CONTAINS find all Terminator the where will eliminate 'Terminator 1'.
Of course the engine is smart enough to start with the CONTAINS not the like condition.