I have 4 columns which I need to concat using , as seperator
I tried below query
Select concat(concat(concat(concat(name,','),age,','),surname,','),city,',') from student
But got the error as
The number of argumemts specified for concat is invalid
Can anyone help me what went wrong
Try instead:
select coalesce(name,'')||','||coalesce(age,'')||','||coalesce(surname,'')||','||coalesce(city,'')||',' from student
The operator || is the concatenation operator, and is usually more readable.
The coalesce() is only needed when the column can contain NULL , because if any of the column do contain NULL then the result of the whole expression will be NULL, so replace them by empty-string or other character of your choice with the coalesce() function.
To use the concat function, which takes two arguments, you can use the below, which you will still need to protect with coalesce() if any of the columns are nullable:
select concat(concat(concat(concat(concat(concat( concat(name,','), age),','),surname),','),city),',') from student;
If the datatype of the columns is CHAR() - which is fixed width, then any leading or trailing spaces will appear in the output. If you do not want these spaces then you must use the TRIM() function on each of these columns. You could avoid this if you had a better design for your table columns , i.e to use VARCHAR as the datatype of the columns that can have variable lenght data because in this case the trailing spaces are automatically removed by the database engine.
Related
I have a requirement where the string from a column has a value "/Date(-34905600000)/". The value within brackets could be in any one of the following patters
"/Date(-34905600000)/"
"/Date(1407283200000)/"
"/Date(1636654411000+0000)/"
I need to extract all inside the parenthesis for examples 1 and 2 including the "-" if any. For the 3rd example, it should be only the numbers inside the parenthesis before "+" ie 1636654411000.
I tried the following and not getting the results as the output is coming along with the parenthesis.
select REGEXP_substr("/Date(-34905600000)/", '\\([[:alnum:]\-]+\\)')
from table A;
select REGEXP_substr("/Date(-34905600000)/", '\\((.*?)\\)') from table
A;
select REGEXP_substr("/Date(-34905600000)/", '[0-9]+') from table A;
Using regexp_replace() instead you could do:
regexp_replace(colA, '(\\/Date\\()([-0-9]*)(.*)', '\\2')
That splits the string into three substitution groups and then only keeps the second. I often end up doing regexp_replace() with substitution groups like this when regexp_substr() fails me.
if you want the REGEXP_SUBSTR to sub-matches you need to use the 'e' <regex_parameters> option, and then you can use 1 as the to match your first grouping, thus:
SELECT column1,
REGEXP_substr(column1, 'Date\\(([-+]?[0-9]+)',1,1,'e')
FROM VALUES
('"/Date(-34905600000)/"'),
('"/Date(1407283200000)/"'),
('"/Date(1636654411000+0000)/"');
gives:
COLUMN1
REGEXP_SUBSTR(COLUMN1, 'DATE\(([-+]?[0-9]+)',1,1,'E')
"/Date(-34905600000)/"
-34905600000
"/Date(1407283200000)/"
1407283200000
"/Date(1636654411000+0000)/"
1636654411000
I am quite sure the regexp is greedy by default, but otherwise you can force the match to the timezone or paren with
'Date\\(([-+]?[0-9]+)[-+\\)]'
I have seen prefix N in some insert T-SQL queries. Many people have used N before inserting the value in a table.
I searched, but I was not able to understand what is the purpose of including the N before inserting any strings into the table.
INSERT INTO Personnel.Employees
VALUES(N'29730', N'Philippe', N'Horsford', 20.05, 1),
What purpose does this 'N' prefix serve, and when should it be used?
It's declaring the string as nvarchar data type, rather than varchar
You may have seen Transact-SQL code that passes strings around using
an N prefix. This denotes that the subsequent string is in Unicode
(the N actually stands for National language character set). Which
means that you are passing an NCHAR, NVARCHAR or NTEXT value, as
opposed to CHAR, VARCHAR or TEXT.
To quote from Microsoft:
Prefix Unicode character string constants with the letter N. Without
the N prefix, the string is converted to the default code page of the
database. This default code page may not recognize certain characters.
If you want to know the difference between these two data types, see this SO post:
What is the difference between varchar and nvarchar?
Let me tell you an annoying thing that happened with the N' prefix - I wasn't able to fix it for two days.
My database collation is SQL_Latin1_General_CP1_CI_AS.
It has a table with a column called MyCol1. It is an Nvarchar
This query fails to match Exact Value That Exists.
SELECT TOP 1 * FROM myTable1 WHERE MyCol1 = 'ESKİ'
// 0 result
using prefix N'' fixes it
SELECT TOP 1 * FROM myTable1 WHERE MyCol1 = N'ESKİ'
// 1 result - found!!!!
Why? Because latin1_general doesn't have big dotted İ that's why it fails I suppose.
1. Performance:
Assume your where clause is like this:
WHERE NAME='JON'
If the NAME column is of any type other than nvarchar or nchar, then you should not specify the N prefix. However, if the NAME column is of type nvarchar or nchar, then if you do not specify the N prefix, then 'JON' is treated as non-unicode. This means the data type of NAME column and string 'JON' are different and so SQL Server implicitly converts one operand’s type to the other. If the SQL Server converts the literal’s type
to the column’s type then there is no issue, but if it does the other way then performance will get hurt because the column's index (if available) wont be used.
2. Character set:
If the column is of type nvarchar or nchar, then always use the prefix N while specifying the character string in the WHERE criteria/UPDATE/INSERT clause. If you do not do this and one of the characters in your string is unicode (like international characters - example - ā) then it will fail or suffer data corruption.
Assuming the value is nvarchar type for that only we are using N''
Requirement:
Need the file to be exported as below format, where gender, age, and interest are columns and value after : is data for that column. Can this be achieved while using Snowflake, if not is it possible to export data using Python
User1234^gender:male;age:18-24;interest:fishing
User2345^gender:female
User3456^age:35-44
User4567^gender:male;interest:fishing,boating
EDIT 1: Solution as given by #demircioglu
It displays as NULL values instead of other column values
Below the EMPLOYEES table data
When I ran below query
SELECT 'EMP_ID'||EMP_ID||'^'||'FIRST_NAME'||':'||FIRST_NAME||';'||'LAST_NAME'||':'||LAST_NAME FROM tempdw.EMPLOYEES ;
Create your SQL with the desired format and write it to a file
COPY INTO #~/stage_data
FROM
(
SELECT 'User'||User||'^'||'gender'||':'||gender||';'||'age'||':'||age||';'||'interest'||':'||interest FROM table
)
file_format = (TYPE=CSV compression='gzip')
File format here is not important because each line will be treated as a field because of your delimiter requirements
Edit:
CONCAT function (aliased with ||) returns NULL if you have a NULL value.
In order to eliminate NULLs you can use NVL2 function
So your SQL will have series of NVL2s
NVL2 checks the first parameter and if it's not NULL returns first expression, if it's NULL returns second expression
So for User column
'User'||User||'^' will turn into
NVL2(User,'User','')||NVL2(User,User,'')||NVL2(User,'^','')
P.S. I am leaving up to you to create the rest of the SQL, because Stackoverflow's function is to help find the solution, not spoon feed the solution.
No, I do not believe multiple delimiters like this are supported in Snowflake at this time. Multiple byte and multiple character delimiters are supported, but they will need to be specified as the same delimiter repeated for either record or line.
Yes, it may be possible to do some post-processing or use Python scripts to achieve this. Or even SQL transformative statements. This is not really my area of expertise so if someone has an example for you, I'll let them add to the discussion.
I am dealing with a table where some columns have special character in it.
I am creating view by concatenating column names in a string and while executing it, it is giving error as 'Invalid column name' at execution statement.I tried with escaping those with escape character but it didn't worked. Tried '&' as an escaping character for '&' in column name.
Please help.
Depending on the special characters, you might be able to resolve this by putting square brackets around the column names:
CREATE TABLE dbo.result([!"£$%^&*()] int,[{}:#~#';'] varchar(50),[<>?/.,] int)
You can use the QUOTENAME function for this purpose:
SELECT QUOTENAME('!"£$%^&*')
Can you give detail ? which are these special characters ?
You can put column names inside [ ]
One of my tables' column contains names, for example as "Obama, Barack" (with double quotes). I was wondering if we can do something to make it appear as Barack Obama in the tables. I think we can do it with declaring a variable but just could not manage to find a solution.
And yes as this table contains the multiple transactions of the same person we also end up with having multiple rows of "Obama, Barack"... a data warehouse concept (fact tables).
What #Ben has said is correct. Having two columns one for first name and one for last name is correct.
However if you wish to update the entire database as it is you could do...
/*This will swap the order round*/
UPDATE TableName SET NameColumn = SUBSTRING(NameColumn, 1, CHARINDEX(',',NameColumn))+SUBSTRING(NameColumn, CHARINDEX(',', NameColumn),LEN(NameColumn)-CHARINDEX('"', NameColumn,2))
/*This will remove the quotes*/
UPDATE TableName SET NameColumn = REPLACE(NameColumn, '"', '')
Edit:- but as I can't see your data you may have to edit it slightly. But the theory is correct. See here http://www.technoreader.com/SQL-Server-String-Functions.aspx
From the question I assume you want to:
Remove the quotes
Remove the comma
Swap the names
So Regexp_replace is probably your best bet
UPDATE tablename
SET column_name = REGEXP_REPLACE( column_name, '^"(\w+), (\w+)"$', '\2 \1' )
So regexp_replace is changing the column value as long as it matches the pattern exactly. What the parts of the expression are
^" means it must start with a double quote
(\w+) means immediately followed by a string of 1 or more alphanumeric characters. This string is then saved as the variable \1 because its the first set of ()
, means immediately followed by a comma and a space
(\w+) means immediately followed by a string of 1 or more alphanumeric characters. This string is then saved as the variable \2 because its the second set of ()
"$ means immediately follwed by a double quote which is the end of the string
\2 \1 is the replacement string, the second saved string followed by a space followed by the first saved string
So anything which does not exactly match these conditions will not be replaced. So if you have an leading or traling spaces, or more than one space after the comma, or many other reasons the text will not be replaced.
A much more flexible (maybe too flexible) option could be:
UPDATE tablename
SET column_name = REGEXP_REPLACE( column_name, '^\W*(\w+)\W+(\w+)\W*$', '\2 \1' )
This is similar but effectively makes the quotes and the comma optional, and deals with any other leading or trailing pubctuation or whitespace.
^\W* means must start with zero or more non-alphanumberics
(\w+)\W+(\w+) means two alphanumberic strings separated by one or more non-alphanumerics. The two strings are saved as described above
\W*$ means must then end with zero or more non-alphanumberics
More info on regexp in oracle is here
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/ap_posix.htm
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14251/adfns_regexp.htm