I am running the following query on an sqlite3 database:
SELECT file.id AS fileID, file.path
FROM file
JOIN (SELECT tag_file_map.fileID,tag.tagname
FROM tag_file_map, tag JOIN tag ON tag_file_map.tagID = tag.id)
ON tag_file_map.fileID = file.id
WHERE tag.tagname = 'tag1' AND tag.tagname= 'tag2';
It gives me the following error: "ambiguous column name: tag.tagname"
Google seems to say that this error is produced when one or more tables share a column name and the specific table of the column is not specified. However, here, the table name IS specified. Plus, there is no other column with the name "tagname" in the entire database, so it shouldn't be ambiguous with or without the table name. Is this an sqlite problem, or is something off with my syntax?
on you inner select, change
FROM tag_file_map, tag JOIN tag on tag_file_map....
to
FROM tag_file_map JOIN tag on tag_file_map....
I think this will work...
SELECT file.id AS fileID, file.path
FROM file
JOIN
(SELECT tag_file_map.fileID, tag.tagname FROM tag_file_map
JOIN tag ON tag_file_map.tagID = tag.id
WHERE tag.tagname = 'tag1' AND tag.tagname= 'tag2')
ON tag_file_map.fileID = file.id;
Related
Is it possible to do the following query in SQLite.Swift without resorting to arbitrary SQL (which I do have working but would prefer to avoid)?
select table1.id, sum(table1.col1*table2.col2)
from table1, table2
where table1.id=table2.id
group by table1.id
I've attempted the following: the SQL (through asSQL()) appears to be correct, but I can't find a way to reference the aggregate column from the returned row.
let query = table1.select(id, (table1[column1]*table2[column2]).sum
.join(table2, on: table1[id] == table2[id])
.group(id)
Can you alias columns somehow?
OK, I've found the solution, and it only took me 2 days!
The way to alias a column in SQLite.swift is to use an expression.
The name of the expression becomes the column alias.
So instead of
let query = table1.select(id, (table1[column1]*table2[column2]).sum)
.join(table2, on: table1[id] == table2[id])
.group(id)
Use:
let aggrColumn = (table1[column1]*table2[column2]).sum
let query = table1.select(id, aggrColumn)
.join(table2, on: table1[id] == table2[id])
.group(id)
let results = try db.prepare(query)
for row in results {
myAggrColumn = try row.get(aggrColumn)
}
Using
select id, sum(table1.col1*table2.col2)
from table1, table2
were table1.id=table2.id
group by id
Will result (see below for corrections) in 2 columns, namely id and sum(table1,col*table2.col2)
However both uses of id would be ambiguous as coded as there are two such source columns.
As such the query should be changed (see following code whihc assumes you want the id from table1 (shouldn't matter if table2 were used due to the join))
Additionally were is not a keyword, it should be WHERE
An alias would likely make things easier you make an alias using the AS keyword. The folloiwng also includes AS mysumcolumn thus the resultant columns will be id and mysumcolumn
select table1.id, sum(table1.col1*table2.col2) AS mysumcolumn
from table1, table2
where table1.id=table2.id
group by table1.id
Running this with no data results in :-
I have a old table and a new table. what i need is to copy the uuId of the old table to the new Table.
im following some answers from other references but i can`t get the ideal answer.
the closest answer i found is this:
update table1
set table1.uuid =
(select table2.uuid from table2 where table1.itemDescription = table2.itemDescription)
when i execute this query, it only saves the 1st found uuid of the old table to all the entry in the new Table.
Sample Table2 (old table):
uuid|itemDescription
1|item1
2|item2
3|item3
Sample Table1 (new Table):
uuid|itemDescription
Null|item1
Null|item2
Null|item3
Desired Output:
uuid|itemDescription
1|item1
2|item2
3|item3
what happens:
uuid|itemDescription
1|item1
1|item2
1|item3
In SQLite, you must not use the table name in the SET clause:
update table1
set uuid =
(select table2.uuid from table2 where table1.itemDescription = table2.itemDescription);
Try like this :
UPDATE table1
SET table1.uuid = table2.uuid
FROM table2 WHERE table1.itemDescription = table2.itemDescription
No need for subquery, otherwise you need to link item description in outer query also
Table A (goradid) has a field which is a FK to Table B(Spriden). I need two sets of data (spriden_id and Goradid_additional_id) from Table A and Table B and insert it into one of the field called e.g. bannerid and partyid. please see my code below as i am also getting a error SQL command not properly ended in PLSQL.
SELECT spriden_id, goradid_additional_id
FROM goradid, spriden
INNER JOIN spriden ON spriden_pidm = goradid_pidm
INTO bannerid, partyid;
The correct syntax is SELECT <COLUMN LIST> INTO <VARIABLE LIST>. So the query should be:
SELECT spriden_id, goradid_additional_id
INTO bannerid, partyid
FROM goradid a INNER JOIN spriden b ON b.spriden_pidm = a.goradid_pidm;
you can use aliasing for this.
it's simple.
SELECT spriden_id as bannerid, goradid_additional_id as partyid FROM goradid INNER JOIN spriden ON spriden_pidm = goradid_pidm;
Note: if you want to use into then you have to initialize the variable.
we use into usually.
declare
v_author author%rowtype;
begin
select * into v_author from author where author_key = 'A103';
dbms_output.put_line('Name:'||v_author.author_first_name||' '|| v_author.author_last_name);
end;
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 have a problem to add a new column to a SQLITE table if this column is not already exist.
I have try with this code but i don’t know why it wont execute:
IF NOT EXISTS(SELECT * FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'mytable' AND COLUMN_NAME = 'mynewcolumn')
BEGIN
ALTER TABLE mytable ADD COLUMN mynewcolumn TEXT
END
I get an Exception error :
error: near "IF": syntax error
This is the solution i select :
1- I do PRAGMA table_info :
pragma table_info(MyTable)
This command gives all the informations about all the columns of the table. each row correspand to the information of a column.
This commande return an output table with 4 columns : cid, name, type, notnull, dft value, pk
2- I read all the rows from "PRAGMA table_info (MyTable)", and i compare the column "name" with the name of the column i want to check if exist.
3- If Column exist then i dont do anything
4- but if the column doen't exist then, here i add the column to my table using this commade :
ALTER TABLE MyTable ADD COLUMN NewColumn TEXT;
this is work for me, and do the job correctly.
To test whether a column exists, execute PRAGMA table_info and check if the column name appears in the result.