I am fairly new to SQL. What I am trying to do is create a view from an existing table. I also need to add a new column to the view which maps to the values of an existing column in the table.
So within the view, if the value in a field for Col_1 = A, then the value in the corresponding row for New_Col = C etc
Does this even make sense? Would I use the CASE clause? Is mapping in this way even possible?
Thanks
The best way to do this is to create a mapping or lookup table
For example consider the following LOOKUP table.
COL_A NEW_VALUE
---- -----
A C
B D
Then you can have a query like this:
SELECT A.*, LOOK.NEW_VALUE
FROM TABLEA AS A
JOIN LOOKUP AS LOOK ON A.COL_A = LOOK.COL_A
This is what DimaSUN is doing in his query too -- but in his case he is creating the table dynamically in the body of the query.
Also note, I'm using a JOIN (which is an inner join) so only results in the lookup table will be returned. This could filter the results. A LEFT JOIN there would return all data from A but some of the new columns might be null.
Generally, a view is an instance of a table/a replica provided that there is no alteration to the original table. So, as per your query you can manipulate the data and columns in a view by using case.
Create View viewname as
Select *,
case when column=a.value then 'C'
....
ELSE
END
FROM ( Select * from table) a
If You have restricted list of replaced values You may hardcode that list in query
select T.*,map.New_Col
from ExistingTable T
left join (
values
('A','C')
,('B','D')
) map (Col_1,New_Col) on map.Col_1 = T.Col_1
In this sample You hardcode 'A' -> 'C' and 'B' -> 'D'
In general case You better may to use additional table ( see Hogan answer )
Related
I have duplicated values in my data. However, from the duplicated values, i only want to store 1 values and remove the rest of same duplicated values.
So far, I have found the solution where they remove ALL the duplicated values like this.
Code:
SELECT ID, a.date as date.A, b.date as date.B,
CASE WHEN a.date <> b.date THEN NULL END AS b.date
except(date.A)
FROM
table1 a LEFT JOIN table2 b
USING (ID)
WHERE date.A = 1
Sample input:
Sample output (Store only 1 values from the duplicated values and remove the rest):
NOTE: query might wrong as it remove all duplicated values.
Considering your screenshot's sample data and your explanation. I understand that you want to remove duplicates from your table retaining only one row of unique data. Thus, I was able to create a query to select only one row of data ignoring the duplicates.
In order to select the rows without any duplicates, you can use SELECT DISTINCT. According to the documentation, it discards any duplicate rows. In addition to this method, CREATE TABLE statement will also be used to create a new table (or replace the previous one) with the new data without duplicates. The syntax is as follows:
CREATE OR REPLACE TABLE project_id.dataset.table AS
SELECT DISTINCT ID, a.date as date.A, b.date as date.B,
CASE WHEN a.date <> b.date THEN NULL END AS b.date
except(date.A)
FROM
table1 a LEFT JOIN table2 b
USING (ID)
WHERE date.A = 1
And the output will be exactly the same as you shared in your question.
Notice that I used CREATE OR REPLACE, which means if you set project_id.dataset.table to the same path as the table within your select, it will replace your current table (in case you have the data coming from one unique table). Otherwise, it will create a new table with the specified new table's name.
You can use aggregation. Something like this:
SELECT ANY_VALUE(a).*, ANY_VALUE(b).*
FROM table1 a LEFT JOIN
table2 b
USING (ID)
WHERE date.A = 1
GROUP BY id, a.date;
For each id/datecombination, this returns an arbitrary matching row froma/b`.
I have an issue where to create a report, I need two tables to join that don't have any way to join. I did find a way they could potentially join, but it's complicated.
There is table A, which contains a column called select_criteria. Here are some examples of 3 values it contains:
SELECT DISTINCT SUM(TRANSCRIPTDETAIL.CREDIT_BILLING) FROM SOMETABLE WHERE (( STUDENTFINANCIAL.TUITION_EXEMPTION = 'EMPFT' ) OR ( STUDENTFINANCIAL.TUITION_EXEMPTION = 'EMPPT' )))
SELECT DISTINCT SUM(TRANSCRIPTDETAIL.CREDIT_BILLING) FROM SOMETABLE WHERE ( STUDENTFINANCIAL.TUITION_EXEMPTION = 'PART50' )
In table B, I have a column called tuition_exemption, which contains values like:
EMPFT
EMPPT
PART50
At the tail end of the whole value within the column in table A, there are the tuition exemption codes that match the values in table B.
Is there a way using MSSQL where I can parse out the codes from the long statement in select_criteria, so that they perfectly match the codes from table B? This is my thought on a way to join up table A and table B like I need to do. The other complication is that there is a 1:many connection between select_criteria and a tuition_exemption value, but a 1:1 connection between a tuition_exemption value and a select_criteria value.
So in the end, the join between the two tables should print, in one example, the same select_criteria value twice (I am referencing the first value in my list above from table A), but in those two rows, the two different tuition_exemption values (EMPFT and EMPPT). Or in the case of table A example 2, it would be printed once and match up to PART50 once.
I am stuck here. I have a statement that successfully grabs the select_criteria values I want:
SELECT select_criteria
WHERE (
select_criteria LIKE '%EMPFT%' OR
select_criteria LIKE '%EMPPT%' OR
select_criteria LIKE '%PART50%' OR
)
But what I need to do is this. When it grabs the select_criteria values I want, I then want to print to a new column in this table the code it matches up to. Those codes are values in table B like 'EMPFT', 'EMPPT' and 'PART50'. That is why I was thinking of basically parsing out the codes from select_criteria, and printing them into the new column in table A. That way table A and table B have a value to match up on and I write run my report. I just don't now how to do it in SQL. I kind of know in Perl, but was hoping to just do all of this in SSMS 2012.
Thanks for any help!
byobob
You can use any expression which returns a boolean as a join criteria. Since LIKE returns a bool, you should be able to just do this:
select *
from tableA
join tableB
on tableA.select_criteria like '%' + tableB.codecolumn + '%'
I have to compare comma separated values with a column in the table and find out which values are not in database. [kind of master data validation]. Please have a look at the sample data below:
table data in database:
id name
1 abc
2 def
3 ghi
SQL part :
Here i am getting comma separated list like ('abc','def','ghi','xyz').
now xyz is invalid value, so i want to take that value and return it as output saying "invalid value".
It is possible if i split those value, take it in temp table, loop through each value and compare one by one.
but is there any other optimal way to do this ??
I'm sure if I got the question right, however, I would personally be trying to get to something like this:
SELECT
D.id,
CASE
WHEN B.Name IS NULL THEN D.name
ELSE "invalid value"
END
FROM
data AS D
INNER JOIN badNames B ON b.Name = d.Name
--as SQL is case insensitive, equal sign should work
There is one table with bad names or invalid values if You prefer. This can a temporary table as well - depending on usage (a black-listed words should be a table, ad hoc invalid values provided by a service should be temp table, etc.).
NOTE: The select above can be nested in a view, so the data remain as they were, yet you gain the correctness information. Otherwise I would create a cursor inside a function that would go through the select like the one above and alter the original data, if that is the goal...
It sounds like you just need a NOT EXISTS / LEFT JOIN, as in:
SELECT tmp.InvalidValue
FROM dbo.HopeThisIsNotAWhileBasedSplit(#CSVlist) tmp
WHERE NOT EXISTS (
SELECT *
FROM dbo.Table tbl
WHERE tbl.Field = tmp.InvalidValue
);
Of course, depending on the size of the CSV list coming in, the number of rows in the table you are checking, and the style of splitter you are using, it might be better to dump the CSV to a temp table first (as you mentioned doing in the question).
Try following query:
SELECT SplitedValues.name,
CASE WHEN YourTable.Id IS NULL THEN 'invalid value' ELSE NULL END AS Result
FROM SplitedValues
LEFT JOIN yourTable ON SplitedValues.name = YourTable.name
How would the SQL statement look like to return the bottom result from the upper table?
The last letter from the key should be removed. It stands for the language. EXP column should be split into 5 columns with the language prefix and the right value.
I'm weak at writing more or less difficult SQL statements so any help would be appreciated!
The Microsoft Access equivalent of a PIVOT in SQL Server is known as a CROSSTAB. The following query will work for Microsoft Access 2010.
TRANSFORM First(table1.Exp) AS FirstOfEXP
SELECT Left([KEY],Len([KEY])-2) AS [XKEY]
FROM table1
GROUP BY Left([KEY],Len([KEY])-2)
PIVOT Right([KEY],1);
Access will throw a circular field reference error if you try to name the row heading with KEY since that is also the name of the original table field that you are deriving it from. If you do not want XKEY as the field name, then you would need to break apart the above query into two separate queries as shown below:
qsel_table1:
SELECT Left([KEY],Len([KEY])-2) AS XKEY
, Right([KEY],1) AS [Language]
, Table1.Exp
FROM Table1
ORDER BY Left([KEY],Len([KEY])-2), Right([KEY],1);
qsel_table1_Crosstab:
TRANSFORM First(qsel_table1.Exp) AS FirstOfEXP
SELECT qsel_table1.XKEY AS [KEY]
FROM qsel_table1
GROUP BY qsel_table1.XKEY
PIVOT qsel_table1.Language;
In order to always output all language columns regardless of whether there is a value or not, you need to spike of those values into a separate table. That table will then supply the row and column values for the crosstab and the original table will supply the value expression. Using the two query solution above we would instead need to do the following:
table2:
This is a new table with a BASE_KEY TEXT*255 column and a LANG TEXT*1 column. Together these two columns will define the primary key. Populate this table with the following rows:
"AbstractItemNumberReportController.SelectPositionen", "D"
"AbstractItemNumberReportController.SelectPositionen", "E"
"AbstractItemNumberReportController.SelectPositionen", "F"
"AbstractItemNumberReportController.SelectPositionen", "I"
"AbstractItemNumberReportController.SelectPositionen", "X"
qsel_table1:
This query remains unchanged.
qsel_table1_crosstab:
The new table2 is added to this query with an outer join with the original table1. The outer join will allow all rows to be returned from table2 regardless of whether there is a matching row in the table1. Table2 now supplies the values for the row and column headings.
TRANSFORM First(qsel_table1.Exp) AS FirstOfEXP
SELECT Table2.Base_KEY AS [KEY]
FROM Table2 LEFT JOIN qsel_table1 ON (Table2.BASE_KEY = qsel_table1.XKEY)
AND (Table2.LANG = qsel_table1.Language)
GROUP BY Table2.Base_KEY
PIVOT Table2.LANG;
Try something like this:
select *
from
(
select 'abcd' as [key], right([key], 1) as id, expression
from table1
) x
pivot
(
max(expression)
for id in ([D], [E])
) p
Demo Fiddle
I have one mdb table with the following structure:
Field1 Field2 Field3 Field4
A ...
B ...
I try to use a query to list all the different fields of row A and B in a result-set:
SELECT * From Table1
WHERE Field1 = 'A'
UNION
SELECT * From Table1
WHERE Field1 = 'B';
However this query has two problems:
it list all the fields including the
identical cells, with a large table
it gives out an error message: too
many fields defined.
How could i get around these issues?
Is it not easiest to just select all fields needed from the table, based on the Field1 value and group on the values needed?
So something like this:
SELECT field1, field2,...field195
FROM Table1
WHERE field1 = 'A' or field1 = 'B'
GROUP BY field1, field2, ....field195
This will give you all rows where field1 is A or B and there is a difference in one of the selected fields.
Oh and for the group by statement as well as the SELECT part, indeed use the previously mentioned edit mode for the query. There you can add all fields (by selecting them in the table and dragging them down) that are needed in the result, then click the 'totals' button in the ribbon to add the group by- statements for all. Then you only have to add the Where-clause and you are done.
Now that the question is more clear (you want the query to select fields instead of records based on the particular requirements), I'll have to change my answer to:
This is not possible.
(untill proven otherwise) ;)
As far as I know, a query is used to select records using for example the where clause, never used to determine which fields should be shown depending on a certain criterium.
One thing that MIGHT help in this case is to look at the database design. Are those tables correctly made?
Suppose you have 190 of those fields that are merely details of the main data. You could separate this in another table, so you have a main table and details table.
The details table could look something like:
ID ID_Main Det_desc Det_value
This way you can filter all Detail values that are equal between the two main values A and B using something like:
Select a.det_desc, a.det_value, b.det_value
(Select Det_desc, det_value
from tblDetails
where id_main = a) as A inner join
(Select Det_desc, det_value
from tblDetails
where id_main = a) as B
on A.det_desc = B.det_desc and A.det_value <> B.det_value
This you can join with your main table again if needed.
You can full join the table on itself, matching identical rows. Then you can filter on mismatches if one of the two join parts is null. For example:
select *
from (
select *
from Table1
where Field1 = 'A'
) A
full join
(
select *
from Table1
where Field1 = 'B'
) B
on A.Field2 = B.Field2
and A.Field3 = B.Field3
where A.Field1 is null
or B.Field1 is null
If you have 200 fields, ask Access to generate the column list by creating a query in design view. Switch to SQL view and copy/paste. An editor with column mode (like UltraEdit) will help create the query.