I have two tables, Engineering table and Instrumentation table. In the Engineering table I have the columns and possible data below:
Tag | Speed Control
PC-1234 |
ME-1235 |
BF-1236 |
In the Instrumentation Table I have the following columns and data
Function | Tag
SC | 1234
SC | 1235
SC | 1237
I want to automate the Speed Control column in the Engineering table to say Yes or No IF there is a line of data in the Instrumentation table with the function as SC and the Tag column have matching data with the number part of the Tag column in the Engineering table. So the results would like like the below:
Tag | Speed Control
PC-1234 | Yes
ME-1235 | Yes
BF-1236 | No
Please help with the best way to do this. Thanks in advance for any help.
You don't want a separate column in the Engineering table for this. You just need a view which you can query
CREATE VIEW EngineeringSpeedControl
AS
SELECT
e.Tag,
SpeedControl = CASE WHEN i.Tag IS NULL THEN 'No' ELSE 'Yes' END
FROM dbo.Engineering e
LEFT JOIN dbo.Instrumentation i
ON i.Tag = RIGHT(e.Tag, LEN(e.Tag) - 3)
AND i.[Function] = 'SC';
Unfortunately, due to the poor design of the tables, you need to muck around with string manipulation.
Ideally you would have the Engineering.Tag column split into separate parts, so you could just do a straight join
LEFT JOIN dbo.Instrumentation i
ON i.Tag = e.Tag
AND i.[Function] = 'SC';
as i don't know if the Tag column in engineers is always of the same format, i keep my query so that it can have similar design xxxxx-nnnnnnnnn with a minus between.
UPDATE [dbo].[Engineering]
SET [Speed Control] =
CASE WHEN EXISTS ( SELECT 1 FROM [dbo].[Instrumentation] i WHERE RIGHT([dbo].[Engineering] .[tag],CHARINDEX('-', (REVERSE([dbo].[Engineering] .[tag]))) - 1) = CAST(i.[Tag] AS VARCHAR(10))) then 'YES' ELSE 'NO' END
WHERE [Speed Control] IS NULL
result will be
Create a function and use a function in calculated columns
create table instrumentation([Function] varchar(200) null, Tag varchar(200) null)
insert into instrumentation values('SC', '1234'),('SC', '1235'),('SC', '1237')
create Function fn_Speed (#tag varchar(200))
returns varchar(200)
as
begin
declare #tagg varchar(200)= (select SUBSTRING(#tag, charindex('-', #tag)+1,10))
declare #result varchar(200)
--return #tagg
If exists (
select 1 from instrumentation where tag =#tagg)
select #result= 'True'
else
select #result= 'False'
return #result
end
Create table engineering (tag varchar(200), Speed as dbo.fn_Speed (tag) )
insert into engineering(tag)values('PC-1234'), ('ME-1235'), ('BF-1236')
Related
I have a column with the following values (there is alot more):
20150223-001
20150224-002
20150225-003
I need to write an UPDATE statement which will change the first 2 characters after the dash to 'AB'. Result has to be the following:
20150223-AB1
20150224-AB2
20150225-AB3
Could anyone assist me with this?
Thanks in advance.
Use this,
DECLARE #MyString VARCHAR(30) = '20150223-0000000001'
SELECT STUFF(#MyString,CHARINDEX('-',#MyString)+1,2,'AB')
If there is a lot of data, you could consider to use .WRITE clause. But it is limited to VARCHAR(MAX), NVARCHAR(MAX) and VARBINARY(MAX) data types.
If you have one of the following column types, the .WRITE clause is easiest for this purpose, example below:
UPDATE Codes
SET val.WRITE('AB',9,2)
GO
Other possible choice could be simple REPLACE:
UPDATE Codes
SET val=REPLACE(val,SUBSTRING(val,10,2),'AB')
GO
or STUFF:
UPDATE Codes
SET val=STUFF(val,10,2,'AB')
GO
I based on the information that there is always 8 characters of date and one dash after in the column. I prepered a table and checked some solutions which were mentioned here.
CREATE TABLE Codes(val NVARCHAR(MAX))
INSERT INTO Codes
SELECT TOP 500000 CONVERT(NVARCHAR(128),GETDATE()-CHECKSUM(NEWID())%1000,112)+'-00'+CAST(ABS(CAST(CHECKSUM(NEWID())%10000 AS INT)) AS NVARCHAR(128))
FROM sys.columns s1 CROSS JOIN sys.columns s2
I run some tests, and based on 10kk rows with NVARCHAR(MAX) column, I got following results:
+---------+------------+
| Method | Time |
+---------+------------+
| .WRITE | 28 seconds |
| REPLACE | 30 seconds |
| STUFF | 15 seconds |
+---------+------------+
As we can see STUFF looks like the best option for updating part of string. .WRITE should be consider when you insert or append new data into string, then you could take advantage of minimall logging if the database recovery model is set to bulk-logged or simple. According to MSDN articleabout UPDATE statement: Updating Large Value Data Types
According to the OP Comment:-
Its always 8 charachters before the dash but the characters after the
dash can vary. It has to update the first two after the dash.
use the next simple code:-
DECLARE #MyString VARCHAR(30) = '20150223-0000000001'
SELECT REPLACE(#MyString,SUBSTRING(#MyString,9,3),'-AB')
Result:-
20150223-AB00000001
try,
update table set column=stuff(column,charindex('-',column)+1,2,'AB')
Declare #Table1 TABLE (DateValue Varchar(50))
INSERT INTO #Table1
SELECT '20150223-000000001' Union all
SELECT '20150224-000000002' Union all
SELECT '20150225-000000003'
SELECT DateValue,
CONCAT(SUBSTRING(DateValue,0,CHARINDEX('-',DateValue)),
REPLACE(LEFT(SUBSTRING(DateValue,CHARINDEX('-',DateValue)+1,Len(DateValue)),2),'00','-AB'),
SUBSTRING(DateValue,CHARINDEX('-',DateValue)+1,Len(DateValue))) AS ExpectedDateValue
FROM #Table1
OutPut
DateValue ExpectedDateValue
---------------------------------------------
20150223-000000001 20150223-AB000000001
20150224-000000002 20150224-AB000000002
20150225-000000003 20150225-AB000000003
To Update
Update #Table1
SEt DateValue= CONCAT(SUBSTRING(DateValue,0,CHARINDEX('-',DateValue)),
REPLACE(LEFT(SUBSTRING(DateValue,CHARINDEX('-',DateValue)+1,Len(DateValue)),2),'00','-AB'),
SUBSTRING(DateValue,CHARINDEX('-',DateValue)+1,Len(DateValue)))
From #Table1
SELECT * from #Table1
OutPut
DateValue
-------------
20150223-AB000000001
20150224-AB000000002
20150225-AB000000003
Wasn't sure how to title the question but hopefully this makes sense :)
I have a table (OldTable) with an index and a column of comma separated lists. I'm trying to split the strings in the list column and create a new table with the indexes coupled with each of the sub strings of the string it was connected to in the old table.
Example:
OldTable
index | list
1 | 'a,b,c'
2 | 'd,e,f'
NewTable
index | letter
1 | 'a'
1 | 'b'
1 | 'c'
2 | 'd'
2 | 'e'
2 | 'f'
I have created a function that will split the string and return each sub string as a record in a 1 column table as so:
SELECT * FROM Split('a,b,c', ',', 1)
Which will result in:
Result
index | string
1 | 'a'
1 | 'b'
1 | 'c'
I was hoping that I could use this function as so:
SELECT * FROM Split((SELECT * FROM OldTable), ',')
And then use the id and string columns from OldTable in my function (by re-writing it slightly) to create NewTable. But I as far as I understand sending tables into the function doesn't work as I get: "Subquery returned more than 1 value. ... not premitted ... when the subquery is used as an expression."
One solution I was thinking of would be to run the function, as is, on all the rows of OldTable and insert the result of each call into NewTable. But I'm not sure how to iterate each row without a function. And I can't send tables into the a function to iterate so I'm back at square one.
I could do it manually but OldTable contains a few records (1000 or so) so it seems like automation would be preferable.
Is there a way to either:
Iterate over OldTable row by row, run the row through Split(), add the result to NewTable for all rows in OldTable. Either by a function or through regular sql-transactions
Re-write Split() to take a table variable after all
Get rid of the function altogether and just do it in sql transactions?
I'd prefer to not use procedures (don't know if there is a solutions with them either) mostly because I don't want the functionality inside of the DB to be exposed to the outside. If, however that is the "best"/only way to go I'll have to consider it. I'm quite (read very) new to SQL so it might be a needless worry.
Here is my Split() function if it is needed:
CREATE FUNCTION Split (
#string nvarchar(4000),
#delimitor nvarchar(10),
#indexint = 0
)
RETURNS #splitTable TABLE (id int, string nvarchar(4000) NOT NULL) AS
BEGIN
DECLARE #startOfSubString smallint;
DECLARE #endOfSubString smallint;
SET #startOfSubString = 1;
SET #endOfSubString = CHARINDEX(#delimitor, #string, #startOfSubString);
IF (#endOfSubString <> 0)
WHILE #endOfSubString > 0
BEGIN
INSERT INTO #splitTable
SELECT #index, SUBSTRING(#string, #startOfSubString, #endOfSubString - #startOfSubString);
SET #startOfSubString = #endOfSubString+1;
SET #endOfSubString = CHARINDEX(#delimitor, #string, #startOfSubString);
END;
INSERT INTO #splitTable
SELECT #index, SUBSTRING(#string, #startOfSubString, LEN(#string)-#startOfSubString+1);
RETURN;
END
Hope my problem and attempt was explained and possible to understand.
You are looking for cross apply:
SELECT t.index, s.item
FROM OldTable t CROSS APPLY
(dbo.split(t.list, ',')) s(item);
Inserting in the new table just requires an insert or select into clause.
I must create an SQL table with 90+ fields, the majority of them are bit fields like N01, N02, N03 ... N89, N90 is there a fast way of creating multiple fileds or is it possible to have one single field to contain an array of values true/false? I need a solution that can also easily be queried.
There is no easy way to do this and it will be very challenging to do queries against such a table. Create a table with three columns - item number, bit field number and a value field. Then you will be able to write 'good' succinct Tsql queries against the table.
At least you can generate ALTER TABLE scripts for bit fields, and then run those scripts.
DECLARE #COUNTER INT = 1
WHILE #COUNTER < 10
BEGIN
PRINT 'ALTER TABLE table_name ADD N' + RIGHT('00' + CONVERT(NVARCHAR(4), #COUNTER), 2) + ' bit'
SET #COUNTER += 1
END
TLDR: Use binary arithmetic.
For a structure like this
==============
Table_Original
==============
Id | N01| N02 |...
I would recommend an alternate table structure like this
==============
Table_Alternate
==============
Id | One_Col
This One_Col is of varchar type which will have value set as
cast(n01 as nvarchar(1)) + cast(n02 as nvarchar(1))+ cast(n03 as nvarchar(1)) as One_Col
I however feel that you'd use C# or some other programming language to set value into column. You can also use bit and bit-shift operations.
Whenever you need to get a value, you can use SQL or C# syntax(treating as string)
In sql query terms you can use a query like
SELECT SUBSTRING(one_col,#pos,1)
and #pos can be set like
DECLARE #Colname nvarchar(4)
SET #colname=N'N32'
-- ....
SET #pos= CAST(REPLACE(#colname,'N','') as INT)
Also you can use binary arithmetic too with ease in any programming language.
Use three columns.
Table
ID NUMBER,
FIELD_NAME VARCHAR2(10),
VALUE NUMBER(1)
Example
ID FIELD VALUE
1 N01 1
1 N02 0
.
1 N90 1
.
2 N01 0
2 N02 1
.
2 N90 1
.
You can also OR an entire column for a fieldname (or fieldnameS):
select DECODE(SUM(VALUE), 0, 0, 1) from table where field_name = 'N01';
And even perform an AND
select EXP(SUM(LN(VALUE))) from table where field_name = 'N01';
(see http://viralpatel.net/blogs/row-data-multiplication-in-oracle/)
I have a table like this:
SKU Size
A 10
B 10
C 10
D 10
E 10
F 10
G 10
I want to change it to:
SKU Size
A 20
B 10
C 30
D 10
E 80
F 10
G 60
I have more than 3000 rows of records to update. How can I do that with SQL update command ?
UPDATE T
SET Size = CASE SKU
WHEN 'A' THEN 20
WHEN 'B' THEN 10
WHEN 'C' THEN 30
WHEN ...
END
Or there may be a formula for calculating the size, but you've failed to give it in your question (Or we may have to switch to a more complex CASE expression, but again, too little detail in the question).
Create a table with the mapping of SKU to new size; update the master table from that.
Many dialects of SQL have a notation for doing updates via joined tables. Some do not. This will work where there is no such notation:
CREATE TABLE SKU_Size_Map
(
SKU CHAR(16) NOT NULL,
Size INTEGER NOT NULL
);
...Populate this table with the SKU values to be set...
...You must have such a list...
UPDATE MasterTable
SET Size = (SELECT Size FROM SKU_Size_Map
WHERE MasterTable.SKU = SKU_Size_Map.Size)
WHERE SKU IN (SELECT SKU FROM SKU_Size_Map);
The main WHERE condition is need to avoid setting the size to null where there is no matching row.
You can probably also do it with a MERGE statement. But the key insight for any of these notations is that you need a table to do the mapping between SKU and size. You either need a table or you need an algorithm, and the sample data doesn't suggest an algorithm.
Make use of OpenXML to resolve your issue
example
declare #i int
exec sp_xml_preparedocument #i output,
'<mydata>
<test xmlID="3" xmlData="blah blah blah"/>
<test xmlID="1" xmlData="blah"/>
</mydata>'
insert into test
select xmlID, xmlData
from OpenXml(#i, 'mydata/test')
with (xmlID int, xmlData nvarchar(30))
where xmlID not in (select xmlID from test)
update test
set test.xmlData = ox.xmlData
from OpenXml(#i, 'mydata/test')
with (xmlID int, xmlData nvarchar(30)) ox
where test.xmlID = ox.xmlID
exec sp_xml_removedocument #i
Just do...
UPDATE [yourTable] SET Size = 20 WHERE SKU = 'A'
And do this for all values you want to change...
Well, if you don't have a formula to calculate your Sizes, and you don't have a file or an Excel sheet with the data that you can massage into your table, you'll just have to get some luckless intern to type something like
UPDATE <table> SET Size = <value> WHERE SKU = '<key>'
3000 times.
If you are that intern, I'd suggest giving us a little more information...
Since you wanted to change the whole column, drop that particular column by using this:
ALTER TABLE table_name
DROP COLUMN column_name;
then create a new column using:
ALTER TABLE table_name
ADD column_name varchar(80);
Check the question This SELECT query takes 180 seconds to finish (check the comments on the question itself).
The IN get to be compared against only one value, but still the time difference is enormous.
Why is it like that?
Summary: This is a known problem in MySQL and was fixed in MySQL 5.6.x. The problem is due to a missing optimization when a subquery using IN is incorrectly indentified as dependent subquery instead of an independent subquery.
When you run EXPLAIN on the original query it returns this:
1 'PRIMARY' 'question_law_version' 'ALL' '' '' '' '' 10148 'Using where'
2 'DEPENDENT SUBQUERY' 'question_law_version' 'ALL' '' '' '' '' 10148 'Using where'
3 'DEPENDENT SUBQUERY' 'question_law' 'ALL' '' '' '' '' 10040 'Using where'
When you change IN to = you get this:
1 'PRIMARY' 'question_law_version' 'ALL' '' '' '' '' 10148 'Using where'
2 'SUBQUERY' 'question_law_version' 'ALL' '' '' '' '' 10148 'Using where'
3 'SUBQUERY' 'question_law' 'ALL' '' '' '' '' 10040 'Using where'
Each dependent subquery is run once per row in the query it is contained in, whereas the subquery is run only once. MySQL can sometimes optimize dependent subqueries when there is a condition that can be converted to a join but here that is not the case.
Now this of course leaves the question of why MySQL believes that the IN version needs to be a dependent subquery. I have made a simplified version of the query to help investigate this. I created two tables 'foo' and 'bar' where the former contains only an id column, and the latter contains both an id and a foo id (though I didn't create a foreign key constraint). Then I populated both tables with 1000 rows:
CREATE TABLE foo (id INT PRIMARY KEY NOT NULL);
CREATE TABLE bar (id INT PRIMARY KEY, foo_id INT NOT NULL);
-- populate tables with 1000 rows in each
SELECT id
FROM foo
WHERE id IN
(
SELECT MAX(foo_id)
FROM bar
);
This simplified query has the same problem as before - the inner select is treated as a dependent subquery and no optimization is performed, causing the inner query to be run once per row. The query takes almost one second to run. Changing the IN to = again allows the query to run almost instantly.
The code I used to populate the tables is below, in case anyone wishes to reproduce the results.
CREATE TABLE filler (
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT
) ENGINE=Memory;
DELIMITER $$
CREATE PROCEDURE prc_filler(cnt INT)
BEGIN
DECLARE _cnt INT;
SET _cnt = 1;
WHILE _cnt <= cnt DO
INSERT
INTO filler
SELECT _cnt;
SET _cnt = _cnt + 1;
END WHILE;
END
$$
DELIMITER ;
CALL prc_filler(1000);
INSERT foo SELECT id FROM filler;
INSERT bar SELECT id, id FROM filler;
It's about inner queries a.k.a subqueries vs joins, not about IN vs =, ant the reasons are explained in that post.
MySQL's version 5.4 is suppposed to introduce an improved optimiser, that can rewrite some subqueries into more efficient form.
The worst thing you can do, is to use so called correlated subquery
http://dev.mysql.com/doc/refman/5.1/en/correlated-subqueries.html
SQL optimizers don't always do what you expect them to do. I'm not sure there's a better answer than that. That's why you have to examine EXPLAIN PLAN output, and profile your queries to find out where the time is spent.
It is interesting but the problem can be also solved with the prepared statements (not sure if it is suitable for everybody), e.g.:
mysql> EXPLAIN SELECT * FROM words WHERE word IN (SELECT word FROM phrase_words);
+----+--------------------+--------------+...
| id | select_type | table |...
+----+--------------------+--------------+...
| 1 | PRIMARY | words |...
| 2 | DEPENDENT SUBQUERY | phrase_words |...
+----+--------------------+--------------+...
mysql> EXPLAIN SELECT * FROM words WHERE word IN ('twist','rollers');
+----+-------------+-------+...
| id | select_type | table |...
+----+-------------+-------+...
| 1 | SIMPLE | words |...
+----+-------------+-------+...
So just prepare the statement in a stored procedure, then execute it. Here is the idea:
SET #words = (SELECT GROUP_CONCAT(word SEPARATOR '\',\'') FROM phrase_words);
SET #words = CONCAT("'", #words, "'");
SET #query = CONCAT("SELECT * FROM words WHERE word IN (", #words, ");";
PREPARE q FROM #query;
EXECUTE q;