I have 3 tables in PostgreSQL.
the first table I have watertracker
1)tablename: watertracker
2)tablename:weighttracker
tablename: handwashtracker
I want to show below data in one query:
where cid is 86 and date is 2020-08-30 of all table data.
To select data from all tables use join clause in the select statement as follows:
select * from watertracker wt
join weighttracker wet on wet.id=wt.cid
join handwashtracker ht on ht.id=wt.cid
where wt.cid=86 and wt.wt_date::date='2020-08-30';
Related
I am using PGAdmin III and postgres 9.6
I have postgres schemas that consists of 250 tables with various columns. Two tables are of similar names and have the same columns, but unique data and IDs. I want to UPDATE one column in both tables with a specific number but choosing which rows get updated is complicated.
I have a script which correctly works on one table at a time, but I wonder if it can be done in a single script. I have tried using DO and LOOP but keep running into roadblocks.
Here's the working single-table script:
UPDATE table1
SET number = 44
WHERE table1.id IN
(SELECT table1.id FROM plan
JOIN name ON name.id = plan.nameid
JOIN type ON type.id = name.typeid
JOIN simul ON simul.id = plan.simulid
LEFT JOIN table1 ON table1.id = tableid
WHERE type.tag = 'X' AND plan.class LIKE '%Table%' AND simul.label IN
('SIMUL90','SIMUL99','SIMUL87'));
"plan.class" contains text which determines class of simul and thus either Table1 or Table2. Table1 and Table2 are of identical column structure but their IDs may be identical so UNION is out of consideration. TH other joins are to fine tune the SELECT so I get only a small subset of the table. The number to update is the same for either table.
I have 3 tables:
table1:{id, uid}
table2:{id, uid}
table1_table2:{table1_id, table2_id}
I need to execute the following queries:
SELECT 1 FROM table1_table2
LEFT JOIN table1 ON table1.id = table1_table2.table1_id
LEFT JOIN table2 ON table2.id = table1_table2.table2_id
WHERE table1.uid = ? and table2.uid = ?
I have unique indices on UUID columns, so I expected the search to be fast. When I have an almost empty database, select takes 0 ms, when there are 50,000 records in table 1, 100 records in table 2 and 110,000 records in table1_table2, select takes 10 ms, which is a lot, because I have to make 400,000 queries. Can I have O(1) on select?
Now I'm using hibernate(spring data) and postgres.
You have unique indices but have you updated statistics with ANALYZE as well?
What type is used for UID column and what type are you feeding it with from Java?
Is there any difference, when you run it from Hibernate/Java and from Postgres console?
Run the query with "EXPLAIN", get the execution plan - from Java as well as from Postgres console, and observe any differences. See How to get query plan information from Postgres into JDBC
I'm having an issue with a simple update statement. I'm new to postgresql and I'm still stuck on MS Sql Server syntax.
What I want to do is to update all records from table1 which are not present / don't exist in table2. Table1 and Table2 are having an 1 to 1 relation. The join column is "colx" from my example
On Ms SQL Server I would have something like this:
UPDATE table1 set col1='some value' from table1 t1 LEFT JOIN table2 t2 on t1.colx=t2.colx WHERE t2.colx IS NULL
or
UPDATE table1 set col1='some value' from table1 t1 where not exists (select 1 from table2 t2 where t1.colx=t2.colx)
My issue is when performing the same on PostgreSql it updates all records from table1, not only the records matching the condition (e.g. I was expecting 4 records to be updated, but all records from table1 are updated instead).
I checked using a select statement the join condition for all possible approaches and I have the expected result (e.g. 4 records).
Is there anything I'm missing?
Your question is not very clear about the requirement.
What I understood is you want to update the value of col1 in table1 for those records which are not present in the table2.
You can try it this way in Postgresql:
UPDATE table1 t1 set col1='some value' where not exists(select 1 from table2 where colx=t1.colx)
DEMO
I have a view and two tables. Tables one and two have the same columns, but table one is has as small number of records, and table two has old data and a huge number of records.
I have to join a view with these two tables to get the latest data from table one; if a record from the view is not available in table one then I have to select the record from table two.
How can i achieve this with MySQL?
I came to know by doing some research in internet that we can't apply full join and sub query in from clause.
Just do a simple UNION of the results excluding the records in table2 that are already mentioned in table1:
SELECT * FROM table1
UNION
SELECT * FROM table2
WHERE NOT EXISTS (SELECT * FROM table1 WHERE table2.id = table1.id)
Something like this.
SELECT *
FROM view1 V
INNER JOIN (SELECT COALESCE(a.commoncol, b.commoncol) AS commoncol
FROM table1 A
FULL OUTER JOIN table2 B
ON A.commoncol = B.commoncol) C
ON v.viewcol = c.commoncol
If you are using Mysql then check here to simulate Full Outer Join in MySQL
are you trying to update the view from two tables where old record in view needs to be overwritten by latest/updated record from table1 and non existant records from table1 to be appended from table2?
, or are you creating a view from two tables?
I am new to postgresql (and databases in general) and was hoping to get some pointers on improving the efficiency of the following statement.
I am inserting data from one table to another, and do not want to insert duplicate values. I have a rid (unique identifier in each table) that are indexed and are Primary Keys.
I am currently using the following statement:
INSERT INTO table1 SELECT * FROM table2 WHERE rid NOT IN (SELECT rid FROM table1).
As of now the table one is 200,000 records, table2 is 20,000 records. Table1 is going to keep growing (probably to around 2,000,000) and table2 will stay around 20,000 records. As of now the statement takes about 15 minutes to run. I am concerned that as Table1 grows this is going to take way to long. Any suggestions?
This should be more efficient than your current query:
INSERT INTO table1
SELECT *
FROM table2
WHERE NOT EXISTS (
SELECT 1 FROM table1 WHERE table1.rid = table2.rid
);
insert into table1
select t2.*
from
table2 t2
left join
table1 t1 on t1.rid = t2.rid
where t1.rid is null