I have 2 tables, one is indexing the other.
I am querying Table#1, and it has one column (string) that has an ID in it that corresponds to a unique row in Table#2. Im trying to write a query in Sqlite that allows me to retrieve the value from Table#2 if the column value in Table#1 is not an empty string.
Kinda like:
"SELECT TMake,TModel,TTrim,IYear,[%q] AS TPart1 FROM AppGuide WHERE TPart1 != ''"
But instead of retrieving the Index value (TPart1) Id like to get the string from Table#2.
Is this possible?
Any help is appreciated.
You could use a correlated subquery:
SELECT TMake,
TModel,
...,
(SELECT stringvalue
FROM Table2
WHERE Table2.ID = Table1.TPart1)
FROM Table1
WHERE Table1.TPart1 != ''
However, these are rather slow to execute, so you'd better use a join (this returns exactly the same result):
SELECT Table1.TMake,
Table1.TModel,
...,
Table2.stringvalue
FROM Table1 LEFT JOIN Table2 ON Table1.TPart1 = Table2.ID
WHERE Table1.TPart1 != ''
If you don't want to get records from Table1 that have no matching Table2 record, drop the LEFT.
Related
I'm working with SQLite and I have two tables:
table1 table2
------------- --------------
id id
value condition
Column "id" contains the same data. And I need to:
UPDATE table1
SET table1.value = 'Some value'
WHERE table2.condition = 'Some condition"
I tried to use JOIN and FROM for linking tables with "id" column, but this isn`t working in SQLite. Please help with syntax.
You need a correlated subquery in the update, something like this:
UPDATE table1
SET value = 'Some value'
WHERE EXISTS (SELECT 1 FROM table2 t2
WHERE t2.id = table1.id AND
t2.condition = 'Some condition');
Method 1 : Considering the two tables you have are "Table1" and "Table2", Updating Table1 can be done using a nested Select statement in which you will be selecting the data you need to update from Table2. For example:
UPDATE Table1
SET StudentID =
(
SELECT RegNo
FROM Table2 t
WHERE StudentID = RegNo
);
You can have a look on this link which solves a similar question : https://dba.stackexchange.com/questions/206317/update-values-in-one-table-from-data-in-another
Method 2 : You can use a table join. Refer the same link given above.
Edit
I would rather explicitly state my problem I'm facing rather than assuming the approach. There could be an easiest solution to my problem.
I need to select records by joining two different table based on the result from another table. And I have to use different joins based on the result from the first table.
If a particular record is present in the first table, I have two use inner join the first table whereas if it's not present, then I have to left join.
bool recordPresent = select exists (select * from firstTable where access_id = 13) as access
if (recordPresent)
results = select * from secondTable s left join firstTable f on f.access_id = s.access_id where f.access_id is null order by access_id
else
results = select * from secondTable s inner join firstTable f on f.access_id = s.access_id
I have the following columns in a SQLite DB.
id,ts,origin,product,bid,ask,nextts
1,2016-10-18 20:20:54.733,SourceA,Dow,1.09812,1.0982,
2,2016-10-18 20:20:55.093,SourceB,Oil,7010.5,7011.5,
3,2016-10-18 20:20:55.149,SourceA,Dow,18159.0,18161.0,
How can I populate the 'next timestamp' column (nextts) with the next timestamp for the same product (ts), from the same source? I've been trying the following, but I can't seem to put a subquery in an UPDATE statement.
UPDATE TEST a SET nextts = (select ts
from TEST b
where b.id> a.id and a.origin = b.origin and a.product = b.product
order by id asc limit 1);
If I call this, I can display it, but I haven't found a way of updating the value yet.
select a.*,
(select ts
from TEST b
where b.id> a.id and a.origin = b.origin and a.product = b.product
order by id asc limit 1) as nextts
from TEST a
order by origin, a.id;
The problem is that you're using table alias for table in UPDATE statement, which is not allowed. You can skip alias from there and use unaliased (but table-name prefixed) reference to its columns (while keeping aliased references for the SELECT), like this:
UPDATE TEST
SET nextts = (
SELECT b.ts
FROM TEST b
WHERE b.id > TEST.id AND
TEST.origin = b.origin AND
TEST.product = b.product
ORDER BY b.id ASC
LIMIT 1
);
Prefixing unaliased column references with the table name is necessary for SQLite to identify that you're referencing to unaliased table. Otherwise the id column whould be understood as the id from the closest[*] possible data source, in which case it's the aliased table (as b alias), while we're interested in the unaliased table, therefore we need to explicitly tell SQLite that.
[*] Closest data source is the one listed in the same query, or parent query, or parent's parent query, etc. SQLite is looking for the first data source (going from inner part to the outside) in the query hierarchy that defines this column.
I am passing datatable as input parameter to stored procedure. Datatable contains id, Name,Lname,Mobileno,EmpId.
Employee table contains [Name],[Lname],[mobno],[Did] as columns.
When user is logged in, his Id come as DId. There are more than 1000 records. Instead of passing that id to datatable, I have created
separete parameter to sp. I want to add records to Employee table, which are not already exist. If combination of mobileno and Did already exists, then
don't insert into Employee table, else insert. Datatable may contain records, which can be duplicate. So I don't want to include that record. I want select only
distinct records and add them to table. I am intrested in mobile no. If there are 10 record having same moble no, I am fetching record, which comes first.
Following code is right or wrong. According to my knowledge, first from clause, then inner join, then where, then select execute. Record get fetched from datatable,
then inner join happens generate result, from that result not from datatable it will check record. So it will give me proper output.
Create Procedure Proc_InsertEmpDetails
#tblEmp EmpType READONLY,
#DId int
as
begin
INSERT INTO Employee
([Name],[Lname],[mobno],[Did])
SELECT [Name],[Lname],[mobno] #DId
FROM #tblEmp A
Inner join (
select min(Id) as minID, mobno from #tblEmp group by mobno
) MinIDTbl
on MinIDTbl.minID = A.ExcelId
WHERE NOT EXISTS (SELECT 1
FROM Employee B
WHERE B.[mobno] = A.[mobno]
AND B.[Did] = #DId )
end
or does I need to change like this
INSERT INTO Employee
([Name],[Lname],[mobno],[Did])
SELECT C.[Name],C.[Lname],C.[mobno], C.D_Id
from
(SELECT [Name],[Lname],[mobno] #DId as D_Id
FROM #tblEmp A
Inner join (
select min(Id) as minID, mobno from #tblEmp group by mobno
) MinIDTbl
on MinIDTbl.minID = A.ExcelId
)C
WHERE NOT EXISTS (SELECT 1
FROM Employee B
WHERE B.[mobno] = C.[mobno]
AND B.[Did] = #DId )
Using SQLite, I am trying to update three columns based on another table (two columns)
The three columns are (Table1):
'AgentCreatedID'
'AgentOwnedID'
'AgentSentID'
The other table (Table2) consists of 'AgentID' and 'Designation'.
If the ID in one of the three columns matches the 'AgentID' in the second table, I want the 'Designation' value to populate. This table is a list of ALL unique IDs and the corresponding designation. Each row of data has a Creator, Owner, and Sender. I need to see what designation that person is from.
In Access, this would look something like this for the first value. I would also need to add the other two values.
UPDATE Table1
LEFT JOIN Table2 ON Table1.AgentCreatedID = Table2.AgentID
SET raw.AgentCreatedID = [ Table2 ]![ Designation];
I am not sure what that ! command is or how it could be used in SQLite.
SQLite does not suport joins in an UPDATE statement.
You have to look up the new value with correlated subqueries:
UPDATE Table1
SET AgentCreatedID = (SELECT Designation
FROM Table2
WHERE AgentID = AgentCreatedID),
AgentOwnedID = (SELECT Designation
FROM Table2
WHERE AgentID = AgentOwnedID),
AgentSentID = (SELECT Designation
FROM Table2
WHERE AgentID = AgentSentID)
The exclamation mark is used to separate the worksheet name from the reference in that worksheet. Here is Microsoft's explanation of cell references.
Now that you know what [ Table2 ]![Designatio] means, you can simplify it to use only the column name.