IF value is in list set value in next column NULL - sql

Question

I have a huge SQL table and need to filter several columns (called Field) if they are in this list:
AAA, BBB, CCC, DDD, EEE
If this is the case, set respective value column to NULL.
Let me give you an example table:
Field1 Value1 Field2 Value2 ...... Field10 Value10
AAA 9A AAA 9A CCC World
BBB 1 KKK 0
ZZZ 9 AAA 9A CCC 42
CCC 7
LLL 9 AAA 3 III 98
KKK 3 AAA 4
DDD 100 AAA Hello CCC 6
Not all Field Value combinations are filled up until Value10. However every column that is named FieldXX must be checked for the list entries. If a cell is equal to a list entry the respective value field should be set NULL. Otherwise the value field remains untouched.
I struggle to figure out the correct CASE statement for this specific issue. I tried the following code:
SELECT CAST(
CASE
WHEN Field* = AAA or BBB or CCC or DDD or EEE
THEN Value* = 0
ELSE Value* = Value*
END AS bit)
FROM dbo.Log
But this query totally fails and it might not be for specific field-value pairs.
Expected Output
Field1 Value1 Field2 Value2 ...... Field10 Value10
AAA 0 AAA 0 CCC 0
BBB 0 KKK 0
ZZZ 9 AAA 0 CCC 0
CCC 0
LLL 9 AAA 0 III 98
KKK 3 AAA 0
DDD 0 AAA 0 CCC 0
Table name is dbo.Log.

Answer 1

If I understood correctly, you are trying to update ValueX columns based on FieldX data.
In that case you need to write Case condition for every column.
You can directly write 10 Case conditions like below
UPDATE A_LOG
SET VALUE1 = CASE WHEN FIELD1 IN ('AAA','BBB','CCC','DDD','EEE' ) THEN 0 ELSE VALUE1 END,
VALUE2 = CASE WHEN FIELD2 IN ('AAA','BBB','CCC','DDD','EEE' ) THEN 0 ELSE VALUE2 END,
VALUE3 = CASE WHEN FIELD3 IN ('AAA','BBB','CCC','DDD','EEE' ) THEN 0 ELSE VALUE3 END
.
.
VALUE10 = CASE WHEN FIELD10 IN ('AAA','BBB','CCC','DDD','EEE' ) THEN 0 ELSE VALUE10 END
Or you can generate Update statement with Dynamic query like below
DECLARE #IN VARCHAR(100)=' IN (''AAA'',''BBB'',''CCC'',''DDD'',''EEE'' )'
, #SQL VARCHAR(MAX) = 'UPDATE A_LOG SET '
SELECT #SQL = #SQL+ VAL FROM
(
SELECT COLUMN_NAME + ' = CASE WHEN FIELD'+ REPLACE(COLUMN_NAME,'VALUE','')
+ #IN+ ' THEN 0 ELSE '+ COLUMN_NAME + ' END,
' VAL
FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'LOG'
AND COLUMN_NAME LIKE 'VALUE%'
)A
SELECT #SQL = SUBSTRING(#SQL,1,LEN(#SQL)-3)
SELECT #SQL
That will give you update statement for every column with a case condition.

Answer 2

I'm pretty certain the wildcard you're trying to use for your CASE WHEN isn't a valid way of using it.
You can use variables to create a SQL string that you can then copy and execute - this way, if you need to increase the number of fields you're checking, you only have to change one part of your code :)
The code below creates the SQL string then prints it out in the console window:
DECLARE #cnt INT = 1;
DECLARE #sql VARCHAR(MAX) = 'SELECT ';
WHILE #cnt <= 10
BEGIN
DECLARE #COLUMN VARCHAR(MAX) = 'Field' + CAST(#cnt AS varchar(max))
DECLARE #VALUE VARCHAR(MAX) = 'Value' + CAST(#cnt AS varchar(max))
SET #sql = #sql + #COLUMN + ', CASE WHEN ' + #COLUMN + '= ''AAA'' OR ' + #COLUMN + '= ''BBB'' OR ' + #COLUMN + '= ''CCC'' OR ' + #COLUMN + '= ''DDD'' OR ' + #COLUMN + '= ''EEE'' THEN 0 ELSE ' + #VALUE + ' END AS ' + #VALUE;
IF #cnt != 10
(SELECT #sql = #sql + ',')
SET #cnt = #cnt +1
END
SET #sql = #sql + ' INTO [dbo].[LogFilter] FROM [dbo].[Log]';
PRINT #sql;
This code below is what is printed out (I have styled it so you can easily read it and truncated it so it doesn't take up the whole screen) :)
SELECT
Field1,
CASE WHEN Field1= 'AAA' OR Field1= 'BBB' OR Field1= 'CCC' OR Field1= 'DDD' OR Field1= 'EEE'
THEN 0 ELSE Value1 END AS Value1,
Field2,
CASE WHEN Field2= 'AAA' OR Field2= 'BBB' OR Field2= 'CCC' OR Field2= 'DDD' OR Field2= 'EEE'
THEN 0 ELSE Value2 END AS Value2,
Field3,
CASE WHEN Field3= 'AAA' OR Field3= 'BBB' OR Field3= 'CCC' OR Field3= 'DDD' OR Field3= 'EEE'
THEN 0 ELSE Value3 END AS Value3,
...
INTO [dbo].[LogFilter] FROM [dbo].[Log]
This SELECT INTO statement above places your filtered information into a brand new table :)

Answer 3

Try this:
Declare #Table Table(Field1 varchar(10), Value1 varchar(10), Field2 varchar(10), Value2 varchar(10) ,Field10 varchar(10) , Value10 varchar(10))
Declare #NewTable Table(Field1 varchar(10), Value1 varchar(10), Field2 varchar(10), Value2 varchar(10) ,Field10 varchar(10) , Value10 varchar(10))
insert into #Table
SELECT 'AAA','9A','AAA','9A','CCC','World' Union All
SELECT 'BBB','1','KKK','0',NULL,NULL Union All
SELECT 'ZZZ','9','AAA','9A','CCC','42' Union All
SELECT 'CCC','7',NULL,NULL,NULL,NULL Union All
SELECT 'LLL','9','AAA','3','III','98' Union All
SELECT 'KKK','3','AAA','4',NULL,NULL Union All
SELECT 'DDD','100','AAA','Hello','CCC','6'
INSERT into #NewTable
Select Field1,CASE WHEN Field1 in ('AAA','BBB','CCC','DDD','EEE') THEN 0 else Value1 end As Value1
,Field2,CASE WHEN Field2 in ('AAA','BBB','CCC','DDD','EEE') THEN 0 else Value2 end As Value2
,Field10,CASE WHEN Field10 in ('AAA','BBB','CCC','DDD','EEE') THEN 0 else Value10 end As Value10
from #Table
Select * from #NewTable

Answer 4

The Case statement wouldn't work in the way that you've written. You need to individually compare the values in each Field and set the value of 'Value' column.
SELECT CAST(
CASE
WHEN Field1 = AAA or BBB or CCC or DDD or EEE
THEN Value1 = 0
ELSE Value1
END AS bit) Value1,
CAST(
CASE
WHEN Field2 = AAA or BBB or CCC or DDD or EEE
THEN Value2 = 0
ELSE Value2
END AS bit) Value2,
.
.
.
.
<need to write separate case statement for each column which is to be compared>
FROM dbo.Log