I need a JPQL for the MySQL query:
SELECT *
FROM table1 t1
INNER JOIN table2 t2
ON t1.id = t2.table1.id
INNER JOIN (SELECT * FROM table1 t3
INNER JOIN table2 t4 ON t3.id = t4.table1.id
WHERE t3.name = 'xxx') subTable
ON t1.number = subTable.number
WHERE t1.number = '5'
AND id = '3'
Your query seems quite pathological, perhaps say what result you are trying to query, and include your object model.
In general, JPQL does not support sub-selects in the from clause, so your query is not directly convertable to JPQL.
You can always just execute it as a JPA native SQL query, since you seem to be comfortable with SQL than JPQL.
Related
Say select id from some_expensive_query is the cte I want to share. Currently I write two sql in a transaction:
with t as (select id from some_expensive_query) select * from t1 join t on t.id =t1.id;
with t as (select id from some_expensive_query) select * from t2 join t on t.id =t2.id;
As you can see, the cte is executed twice but I want something like:
t = select id from some_expensive_query;
select * from t1 join t on t.id =t1.id;
select * from t2 join t on t.id =t2.id;
for portability, I don't want to use pgsql or functions, anyway to solve this?
Why don't you use union all ?
with t as (select id from some_expensive_query)
select * from t1 join t on t.id =t1.id
union all
select * from t2 join t on t.id =t2.id;
I'm currently migrating from SQL Server to PostgreSQL and got confuse with update query in postgres.
I have query like this in SQL Server:
UPDATE t1
SET col1 = 'xx'
FROM table1 t1
LEFT JOIN table2 t2 ON t1.id = t2.id
WHERE t2.id is null
how do you do this in postgres?
thanks in advance
The left join is used to simulate a "NOT EXISTS" condition, so you can rewrite it to:
update table1 t1
set col1 = 'xx'
where not exists (select *
from table2 t2
where t1.id = t2.id);
As a side note: Postgres works differently than SQL Server and in general you should not repeat the target table of an UPDATE statement in the FROM clause in Postgres.
how to use where clause in join usinq linq for the following T-SQL query?
select * from
tbl1 inner join tbl2
on tbl1.id = tbl2.id
where tdl1.col = tbl2.col
After writing a lot of linq queries I finally found the answer...
from t1 in tbl1
from t2 in tbl2
where t1.id == t2.id && t1.col1 == t2.col2
select new {
Anything...
}
Is there such thing like conditional join:
SELECT *
FROM TABLE1 A
IF (a=='TABLE2') THEN INNER JOIN TABLE2 B ON A.item_id=B.id
ELSE IF (a=='TABLE3') THEN INNER JOIN TABLE3 C ON A.item_id=C.id
While a is a field in TABLE1.
I like to use this in stored procedures without using dynamic sql (without writing query as string and EXEC(#query)).
EDIT: I can't write:
IF (a=='TABLE2) THEN queryA
ELSE IF (a=='TABLE3') THEN queryB
Because a is a field of TABLE1.
EDIT: Modified answer based on comment below:
You could try to get clever with some left joins. This will return more columns, so you'd probably want to be more discriminating than just SELECT *.
SELECT *
FROM TABLE1 A
LEFT JOIN TABLE2 B
ON A.item_id = B.id
AND A.a = 'TABLE2'
LEFT JOIN TABLE3 C
ON A.item_id = C.id
AND A.a = 'TABLE3'
WHERE (B.id IS NOT NULL AND A.a = 'TABLE2')
OR (C.id IS NOT NULL AND A.a = 'TABLE3')
Updated the query as requried:
SELECT * FROM
(
SELECT *
FROM TABLE1 A INNER JOIN TABLE2 B
ON A.a='TABLE2' --This will eleminate the table rows if the value of A.a is not 'TABLE2'
AND A.item_id=B.id) A,
(SELECT * FROM
INNER JOIN TABLE3 C
ON A.a='TABLE3' --This will eleminate the table rows if the value of A.a is not 'TABLE3'
AND A.item_id=C.id
) B
) a
I wrote this, and it is wrong syntax, help me fix it, I want 'T' to be an alias of the result of the two inner joins.
select T.id
from table1
inner join table2 on table1.x = table2.y
inner join table3 on table3.z = table1.w as T;
You cannot use aliases to name the "entire" join, you can, however, put aliases on individual tables of the join:
select t1.id
from table1 t1
inner join table2 t2 on t1.x = t2.y
inner join table3 t3 on t3.z = t1.w
In the projection, you will have to use the alias of the table, which defines the id column you are going to select.
You can't directly name the result of a join. One option is to use a subquery:
select T.id
from (
select *
from table1
inner join table2 on table1.x = table2.y
inner join table3 on table3.z = table1.w
) T
Another option is subquery factoring:
with T as (
select *
from table1
inner join table2 on table1.x = table2.y
inner join table3 on table3.z = table1.w
)
select T.id
from T