first off, noob alert! :))
I need to construct a query that runs on many tables. The tables vary on name just on the last digits as per client code. The thing is, the values that change aren't sequential so looping as in i=1,2,3,... does not work. A possible solution would be to have those values on a given field on an other table.
Here is the code for the first two clients 015 and 061. The leading zero(s) must are essential.
SELECT LnMov2017015.CConta, RsMov2017015.DR, RsMov2017015.NInt, "015" AS CodCli
FROM LnMov2017015 INNER JOIN RsMov2017015 ON LnMov2017015.NReg = RsMov2017015.NReg
WHERE (((LnMov2017015.CConta)="6" And (LnMov2017015.CConta)="7") AND ((RsMov2017015.DR)=9999))
UNION SELECT LnMov2017061.CConta, RsMov2017061.DR, RsMov2017061.NInt, "061" AS CodCli
FROM LnMov2017061 INNER JOIN RsMov2017061 ON LnMov2017061.NReg = RsMov2017061.NReg
WHERE (((LnMov2017061.CConta)="6" And (LnMov2017061.CConta)="7") AND ((RsMov2017061.DR)=9999))
...
So for the first SELECT the table Name is LnMov2017015, the ending 015 being the value, the client code, that changes from table to table e.g. in the second SELECT the table name is LnMov2017061 (061) being what distinguishes the table.
For each client code there are two tables e.g. LnMov2017015 and RsMov2017015 (LnMov2017061 and RsMov2017061 for the second set client shown).
Is there a way that I can build the SQL, based upon the example SQL above?
Does anyone have an idea for a solution? :)
Apparently it is possible to build a query object to read data in another db without establishing table link. Just tested and to my surprise it works. Example:
SELECT * FROM [SoilsAgg] IN "C:\Users\Owner\June\DOT\Lab\Editing\ConstructionData.accdb";
I was already using this structure in VBA to execute DELETE and UPDATE action statements.
Solution found :)
Thank you all for your input.
Instead of linking 100 tables (password protected), I'll access them with SLQ
FROM Table2 IN '' ';database=C:\db\db2.mdb;PWD=mypwd'
And merge them all with a query, before any other thing!
Related
So perhaps the title is a little confusing. If you can suggest better wording for that please let me know and i'll update.
Here's the issue. I've got a table with many thousands of rows and i need to update a few thousand of those many to store latest email data.
For example:
OldEmail#1.com => NewEmail#1.com
OldEmail#2.com => NewEmail#2.com
I've got a list of old emails ('OldEmail#1.com','OldEmail#2.com') and a list of the new ('NewEmail#1.com','NewEmail#2.com'). The HOPE was was to sort of do it simply with something like
UPDATE Table
SET Email = ('NewEmail#1.com','NewEmail#2.com')
WHERE Email = ('OldEmail#1.com','OldEmail#2.com')
I hope that makes sense. Any questions just ask. Thanks!
You could use a case expression:
update mytable
set email = case email
when 'OldEmail#1.com' then 'NewEmail#1.com'
when 'OldEmail#2.com' then 'NewEmail#2.com'
end
where email in ('OldEmail#1.com','OldEmail#2.com')
Or better yet, if you have a large list of values, you might create a table to store them (like myref(old_email, new_email)) and join it in your update query, like so:
update t
set t.email = r.new_email
from mytable t
inner join myref r on r.old_email = t.email
The actual syntax for update/join does vary accross databases - the above SQL Server syntax.
With accuracy to the syntax in particular DBMS:
WITH cte AS (SELECT 'NewEmail#1.com' newvalue, 'OldEmail#1.com' oldvalue
UNION ALL
SELECT 'NewEmail#2.com', 'OldEmail#2.com')
UPDATE table
SET table.email = cte.newvalue
FROM cte
WHERE table.email = cte.oldvalue
or, if CTE is not available,
UPDATE table
SET table.email = cte.newvalue
FROM (SELECT 'NewEmail#1.com' newvalue, 'OldEmail#1.com' oldvalue
UNION ALL
SELECT 'NewEmail#2.com', 'OldEmail#2.com') cte
WHERE table.email = cte.oldvalue
Consider prepared statement for rows update in large batches.
Basically it works as following :
database complies a query pattern you provide the first time, keep the compiled result for current connection (depends on implementation).
then you updates all the rows, by sending shortened label of the prepared function with different parameters in SQL syntax, instead of sending entire UPDATE statement several times for several updates
the database parse the shortened label of the prepared function , which is linked to the pre-compiled result, then perform the updates.
next time when you perform row updates, the database may still use the pre-compiled result and quickly complete the operations (so the first step above can be skipped).
Here is PostgreSQL example of prepare statement, many of SQL databases (e.g. MariaDB,MySQL, Oracle) also support it.
I feel like this should be simple but I'm relatively unskilled in SQL and I can't seem to figure it out. I'm used to wrangling data in python (pandas) or Spark (usually pyspark) and this would be a one-liner in either of those. Specifically, I'm using Snowflake SQL, but I think this is probably relevant to a lot of flavors of SQL.
Essentially I just want to trim the first character off of a specific column. More generally, what I'm trying to do is replace a column with a substring of the same column. I would even settle for creating a new column that's a substring of an existing column. I can't figure out how to do any of these things.
On obvious solution would be to create a temporary table with something like
CREATE TEMPORARY TABLE tmp_sub AS
SELECT id_col, substr(id_col, 2, 10) AS id_col_sub FROM table1
and then join it back and write a new table
CREATE TABLE table2 AS
SELECT
b.id_col_sub as id_col,
a.some_col1, a.some_col2, ...
FROM table1 a
JOIN tmp_sub b
ON a.id_col = b.id_col
My tables have roughly a billion rows though and this feels extremely inefficient. Maybe I'm wrong? Maybe this is just the right way to do it? I guess I could replace the CREATE TABLE table2 AS... to INSERT OVERWRITE INTO table1 ... and at least that wouldn't store an extra copy of the whole thing.
Any thoughts and ideas are most welcome. I come at this humbly from the perspective of someone who is baffled by a language that so many people seem to have mastery over.
I'm not sure the exact syntax/functions in Snowflake but generally speaking there's a few different ways of achieving this.
I guess the general approach that would work universally is using the SUBSTRING function that's available in any database.
Assuming you have a table called Table1 with the following data:
+-------+-----------------------------------------+
Code | Desc
+-------+-----------------------------------------+
0001 | 1First Character Will be Removed
0002 | xCharacter to be Removed
+-------+-----------------------------------------+
The SQL code to remove the first character would be:
select SUBSTRING(Desc,2,len(desc)) from Table1
Please note that the "SUBSTRING" function may vary according to different databases. In Oracle for example the function is "SUBSTR". You just need to find the Snowflake correspondent.
Another approach that would work at least in SQLServer and MySQL would be using the "RIGHT" function
select RIGHT(Desc,len(Desc) - 1) from Table1
Based on your question I assume you actually want to update the actual data within the table. In that case you can use the same function above in an update statement.
update Table1 set Desc = SUBSTRING(Desc,2,len(desc))
You didn't try this?
UPDATE tableX
SET columnY = substr(columnY, 2, 10 ) ;
-Paul-
There is no need to specify the length, as is evidenced from the following simple test harness:
SELECT $1
,SUBSTR($1, 2)
,RIGHT($1, -2)
FROM VALUES
('abcde')
,('bcd')
,('cdef')
,('defghi')
,('e')
,('fg')
,('')
;
Both expressions here - SUBSTR(<col>, 2) and RIGHT(<col>, -2) - effectively remove the first character of the <col> column value.
As for the strategy of using UPDATE versus INSERT OVERWRITE, I do not believe that there will be any difference in performance or outcome, so I might opt for the UPDATE since it is simpler. So, in conclusion, I would use:
UPDATE tableX
SET columnY = SUBSTR(columnY, 2)
;
I am trying to read some exiting SQL queries written for MS SQL server.
I don't have access to database, table names etc.. Just raw query format...And I need to do some analysis on the fields required..
I need some help in understanding what certain query statements are doing...such as in the following block...
select FIELD1, x2.FIELD2
into #temp
from #temp1 x1 join #temp2 x2
on x1.FIELD1 = x2.FIELD2
and x1.FIELD3 = x2.MAXOCCUR
I have basic SQL understanding.. But I need to understand couple of things....Why does 'into' and 'from' statements have a '#' infront of table names.....what are x1 and x2 in this case. Why not just say
temp1.FIELD1 = temp2.FIELD2 instead of
x1.FIELD1 = x2.FIELD2
.....Am I missing something or is this query formed weird to begin with....I understand joins etc...
Can someone help me out...
Thanks
That is selecting from two already temp existing temp tables into a new temp table. The x1.FIELD1 is called aliasing. It's used so you don't have to type full table names when writing the query
As mentioned, the # signs indicate a TEMPORARY table.
x1 and x2 are used as "table alias" in this query. Yes, you could write
temp1.FIELD1 = temp2.FIELD2 instead of x1.FIELD1 = x2.FIELD2
but, consider if the tables had long names. Then using an alias makes the query easier to read (for humans. the computer doesn't really care).
I have a table which has essentially boolean values in a legacy database. The column names are stored as string values in another table so I need to match the column names of one table to a string value in another table. I know there has to be a way to do this directly with SQL in SQL Server but it is beyond me.
My initial thought was to use PIVOT but it is not enabled by default and enabling it would likely be a difficult process with pushing that change to the Production database. I would prefer to use what is enabled by default.
I am considering using COALESCE to translate the boolean value to the string that value that I need. This will be a manual process.
I think I will also use a table variable to insert the results of the first query into that variable and use those results to do the second query. I still have the problem that the columns are on a single row so I wish I could easily pivot the values to put the column names in the result set as strings. But if I could easily do that I could easily write the query with a sub-select.
Any tips are welcome.
Checkout Sysobjects and SysColumns in SQL Server. They are 2 SQL tables that gives you the names of the tables in your DB and the names of the columns that go with that table.
The system view INFORMATION_SCHEMA.COLUMNS will also give you what you want.
You can build a SQL string and then execute that string as a query. Not the prettiest by any means but I think it would work the way you want it to. You would just use a cursor or while loop to build the string.
If you're comfortable with .Net you could just write your own stored proc in your language of choice and manipulate the data in code instead.
Heres a link to get started
CLR Stored Procedures
I'm not quite sure I understand how your design is currently put together (could you post an example?), but the information_schema.columns view will give you a table containing all the column names as string values. If you join your second table against that I think you'll probably get what you need.
For Example, i have a table STATEtbl having 3 columns and i want to get all the column names of this table as ROW values... i use the below query
Select SC.name as Columns from Syscolumns SC
Join Sysobjects SO On SC.id = SO.Id
where Object_name(SO.Id) = 'STATEtbl'
Result of the query:
Columns
--------
State
StateCode
StateFullName
I have the same copy of access running in 3 cities right now. They work perfectly ok. They are 99% the same with one minor difference. Each of them has two views which use different odbc connection to different cities DB (all these databases are SQL Server 2005). The views act as datasource for some two very simple queries.
However, while I tried to make a new copy for a new city, I found that one of the simple internal query returns the correct number of row but all data are empty while the other query functions correctly.
I checked the data of these two views, the data is correct.
The one causing problem are like
Select * from View_Top where Name = "ABC"
when the recordset returns, even rs!Name give me an empty string.
Please help
Well the query looks a little wrong to me, try using ' instead of " to delimit your ABC string...
Without the definition of VIEW_TOP it's hard to tell where your error is, but if you're getting rows but the columns are NULL I'm guessing that VIEW_TOP (or something it depends on) includes an OUTER JOIN and you're pulling the columns from the wrong side of the JOIN.
SELECT
acc.FIRM,
acc.OFFICE,
acc.ACCOUNT,
a.CONV_CODE,
a.OTHER_AMT AS AMOUNT,
a.TRANS_DATE,
a.DESCRIPTN,
a.JRNAL_TYPE
FROM AccTrans AS a LEFT OUTER JOIN ACC AS acc ON a.ACCNT_CODE = acc.ACCNT_CODE
WHERE
(acc.SUN_DB = 'IF1') AND
(ANAL_T0 <> '') AND
(a.TRANS_DATE < '20091022') AND
(a.JRNAL_TYPE = 'MATCH');
This is the definition of the view. Indeed, in Access i am able to view the result of this query, it has data. that's why i know the recordset returns the correct number of row (by counting the loop in the code). sorry for my mistakes, i use Account in the where clause, the select statements should be like
select Firm, Office, Account, Trans_Date.... from
view_top
where account = 'ABC'
the query returns the right number of row but all row data (even the account field) are empty string.
then i found out what really cause the problem is the AMOUNT field, if i omit the amount, everything works. though i don't understand why.
view_top definition
"Name, Account, AccountCode, Amount, Date...."
Select Statements:
Select Name, Account, AccountCode, Amount, Date
From View_Top Where Name = 'xxx'
I found that if I omit the Amount, everything works.
Though I still don't understand why.