Duplicate table name (csuser.t2) in the FROM clause in inner join - sql

Below is the query which is throwing error : as Duplicate table name (csuser.t2) in the FROM clause in inner join
SELECT t1.rxno,
t1.txno,
t2.create_datetime FROM mrgrxtxt t1,rx t2
INNER JOIN (
SELECT rxno,
t1. MIN(txno) AS min_txno,
t2. MAX(create_datetime) AS latest_txno
FROM mrgrxtxt t1 , rx t2
GROUP BY 1
) t2 ON t1.rxno = t2.rxno WHERE t2.min_txno > 8
AND t2.create_datetime = t2.latest_txno;
Can anybody helpout here?? This is informix DB.

You have defined two aliases as t2 one for rx and another for the sub query. Try changing the second t2 to something else like t3.
SELECT t1.rxno,
t1.txno,
t2.create_datetime
FROM mrgrxtxt t1
JOIN rx t2 ON t1.rxno = t2.rxno
INNER JOIN(
SELECT rxno,
t1. MIN(txno) AS min_txno,
t2. MAX(create_datetime) AS latest_txno
FROM mrgrxtxt t1
JOIN rx t2 ON t1.rxno = t2.rxno
GROUP BY 1
) t3 ON t1.rxno = t3.rxno
WHERE t3.min_txno > 8 AND t2.create_datetime = t3.latest_txno;

Related

Inner join the tables where the value of one column is different. But the meaning of the values are same

Table t1
Table t2
I tried running the query
select CountyCode, ContactPerson
from table1 t1
inner join select * from table 2 t2 on t1.CountyCode[1] = Code[0]
Any one help me please.
Use this syntax:
select CountyCode, ContactPerson
from t1
inner join t2 on t1.CountyCode = t2.Code

SQL JOIN USING and WHERE

This is somewhat of a followon to SQL JOIN where to place the WHERE condition?
I would prefer to use the USING clause on the join, but am not yet able to put the field value condition with the join.
SELECT 1
FROM table1 t1
JOIN table2 t2 USING(id) AND t2.field = 0;
ORA-00933: SQL command not properly ended
Is it possible to have USING and another condition as part of the JOIN clause?
You can use:
SELECT 1
FROM table1 t1
JOIN table2 t2 USING(id)
WHERE t2.field = 0;
Using USING(id) is like using ON t1.id = t2.id except that in the JOIN result instead of two columns t1.id & t2.id there is only one id column.
For INNER JOIN USING with a condition followed by an OUTER JOIN you need a subquery to keep the WHERE with the USING:
SELECT ...
FROM (SELECT id, ...
FROM table1 t1
JOIN table2 t2 USING(id)
WHERE t2.field = 0) s
LEFT JOIN ...;
For an OUTER JOIN USING with a condition you need a subselect:
SELECT ...
FROM table1 t1
LEFT JOIN (SELECT *
FROM table2 t2
WHERE t2.field = 0) t2
USING (id);
See this re ON/WHERE with JOIN. See this re ON/WHERE when mixing INNER & OUTER JOINs.

SQL: Calculating the Max date across multiple tables

I am trying to find the max date across multiple columns (in multiple tables). I have an SQL query that I think is almost workable, but am having a hard time debugging it. The problem is that it never returns anything. Any ideas on what I'm doing incorrectly? I don't get any errors, just an empty row "maxdate."
Here's my query:
SELECT
(
SELECT MAX(dates) FROM
(
SELECT dates = t1.UpdateDate
UNION ALL
SELECT dates = t2.UpdateDate
UNION ALL
SELECT dates = t3.UpdateDate
UNION ALL
SELECT dates = t4.UpdateDate
) as dateAcrossColumns
) as maxdate
FROM table1 as t1
join table2 as t2 on t1.ID = t2.ID
join table3 as t3 on t1.ID = t3.ID
join table4 as t4 on t1.ID = t4.ID
join table5 as t5 on t1.Status = t5.Status
WHERE t1.id = #param and t5.status <> 3
First join you join to table 2 using table 1's ID and table 3's ID. I presume you mean table 1's ID and table 2's ID?
join table2 as t2 on t1.ID = t3.ID
Should be:
join table2 as t2 on t1.ID = t2.ID
Now that this has been changed;
I tried your query and it works fine, are you sure that your joins are bringing back any rows? To test it replace your SELECT statement with SELECT *, if you get no rows back then they are being filtered out somewhere in your joins / WHERE.
If it's possible for any of the tables to not have any rows for the given #param, the (inner) joins will filter out all of the other tables.
Try unioning the dates and get the max of the unions
WITH allDates AS (
SELECT UpdateDate
FROM Table1
WHERE ID = #param
UNION
SELECT UpdateDate
FROM Table2
WHERE ID = #param
UNION
SELECT UpdateDate
FROM Table3
WHERE ID = #param
UNION
SELECT UpdateDate
FROM Table4
WHERE ID = #param
UNION
SELECT t5.UpdateDate
FROM Table5 AS t5
JOIN Table1 AS t1
ON t5.Status = t1.Status
WHERE t1.ID = #param
)
SELECT MAX( UpdateDate ) AS MaxDate
FROM allDates
Cant think of a simpler way of doing this :)
SELECT MAX(Dates) AS RequiredDate
FROM (
SELECT t1.UpdateDate AS DateOne
,t2.UpdateDate AS DateTwo
,t3.UpdateDate AS DateThree
,t4.UpdateDate AS DateFour
FROM table1 as t1
join table2 as t2 on t1.ID = t2.ID
join table3 as t3 on t1.ID = t3.ID
join table4 as t4 on t1.ID = t4.ID
join table5 as t5 on t1.[Status] = t5.[Status]
WHERE t1.id = #param and t5.[Status] <> 3
)t
UNPIVOT (Dates FOR DateCols
IN (DateOne, DateTwo,DateThree,DateFour))up
I was trying to solve a similar problem to find the last modified date across a set of joined tables in MySQL. The following worked for me using a combination of GREATEST and MAX:
SELECT GREATEST(MAX(t1.modified), MAX(t2.modified), MAX(t3.modified),
MAX(t4.modified)) AS lastmodified
FROM `table1` AS t1
LEFT JOIN `table2` AS t2 ON t1.id = t2.t1_id
LEFT JOIN `table3` AS t3 ON t2.id = t3.t2_id
LEFT JOIN `table4` AS t4 ON t3.id = t4.t3_id
WHERE t1.id = #param

SQL query - filter with cascading conditions

I've two tables T1 and T2 with the following columns -
T1
Project_ID
Category
Column_X
Column_Y
Column_Z
T2
Proj_ID
Category
Parent_Project_ID
I want to write a query to get records from T1 with the following condition -
Get Projects with Category = "A" from T1
Get child projects of the above filtered projects
I'm not sure how to check the second condition only with the results coming out of first condition.
What is needed?
Projects from T1 where Category is A
Child projects of projects obtained from condition 1
Adding sample data and desired results as requested -
To get all records from second table then you can use the following query.
SELECT
t2.*
FROM T1 t1
RIGHT OUTER JOIN T2 t2 ON t1.Project_ID = t2.Project_ID
WHERE t1.Category = "A"
SELECT * FROM T2 WHERE T2.Proj_ID IN ( SELECT Project_ID FROM T1 WHERE Category = 'A' )
This should do the job needed.
SELECT * from T2 as d
WHERE EXISTS ( SELECT * from T1 as d1 where d1.Category = 'A' and d1.Project_ID = d.Proj_ID )
SELECT * from T1 as d1 right join T2 as d2 on d1.Project_ID = d2.Proj_ID
WHERE d1.CodTert = 500
I've made an update, these query give the same result, one uses the JOIN one doesn't.
I'm assuming that T2.Parent_Project_ID and T1.Project_ID are related. If so, you can use this:
Select T3.*
From T1
Join T2 On T2.Parent_Project_ID = T1.Project_ID
Join T1 T3 On T3.Project_ID = T2.Proj_ID
Where T1.Category = 'A'
This would get only child projects of projects that have a category of 'A'.
EDIT:
Based on the output format that has been added to the question, the following query, which uses a LEFT OUTER JOIN would render the exact result required:
SELECT
T2.PROJ_ID Project_ID,
T2.Category,
T1.Column_X,
T1.Column_Y,
T1.Column_Z,
T2.Parent_Project_ID
FROM T1 T1_PARENTS
INNER JOIN T2
ON T2.Parent_Project_ID = T1.Project_ID and T1.Category = 'A'
INNER JOIN T2 T2_CHILDREN
ON T2_CHILDREN.PROJ_ID = T2.Parent_Project_ID OR T2_CHILDREN.Parent_Project_ID = T2.Parent_Project_ID
LEFT OUTER JOIN T1
ON T2_CHILDREN.PROJ_ID = T1.Project_ID;

SQL Joining three tables and using LEFT OUTER JOIN

I have three tables and two seperate SQL queries which are working correctly and I am having correct results.
If I try to join these three tables I am having null as result.
First query:
select T1.ID,T3.COMPANY
from T1,T3
where (T1.status!='CLOSED') and (T1.PRIORITY)>5 and T1.CLASSID=T3.CLASSID
Second query:
SELECT T1.ID, T2.DESCRIPTION
FROM T1
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY
WHERE T1.status!='CLOSED'
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE)
FROM T2
WHERE T2.KEY=T1.ID))
I tried to join them but as result I am having null:
select T1.ID,T3.COMPANY,T2.DESCRIPTION
from T1
INNER JOIN T3 ON T1.CLASSID=T3.CLASSID
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY
where (T1.status!='CLOSED') AND (T1.PRIORITY)>5
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE)
FROM T2
WHERE T2.KEY=T1.ID))
like it does not recognized last part for taking MAX value from T2 table.
What am I doing wrong? Thanks for help
Firstly, use an alias for the subquery on table T2.
T2.CREATEDATE =
(SELECT MAX(T2Alias.CREATEDATE)
FROM T2 AS T2Alias
WHERE T2Alias.KEY = T1.ID)
Secondly, consider moving this condition into the ON clause of the LEFT JOIN to table T2.
The first thing that jumps out at me is the new dependency on both T1.Priority > 5 and T2.CreateDate value being equal to the result of the inline query:
( AND (T1.PRIORITY) > 5
AND (T2.CREATEDATE =
(SELECT MAX(CREATEDATE) FROM T2 WHERE T2.KEY = T1.ID) )
Without the data it's difficult to check however this may be the issue