I want to bring in data from table a into table b every day.
Both tables have same schema.
I can either use MERGE (WHEN NOT MATCHED THEN INSERT) or I can do an INSERT of the result obtained by doing a left join of table a and table b on id where b.id is null.
Are these both approaches effectively the same?
Related
I want to compare rows value from one table with rows value from another table. Structure of the first table is :
The other table is more complex than first table and have the same structure but number of rows is million rows, by the way first have 60.000 rows.
I need to compare these two tables by biling_profiles so I have an insight into the price but that billing profile turn in the column. It's easily done using the left outer join because approximately 6 or 7 billing_profiles . Next thing I need is that if the other table has no value (for example, the first table has row with (destination 201425, cost 2,624) and the other does not , then I have trimmed one character from right to left and then search (destination - 20142). If no again result i repeat again trim from right to left (destination - 2014), when i found same destination then show in table)
So, how to solve that ?
try
SELECT DISTINCT A.Id
FROM
table1 A
INNER JOIN table 2B
ON A.Id = B.Id AND A.biling_profiles = B.biling_profiles
or
select t1.biling_profiles,t2.biling_profiles
from table1 t1
inner join table2 t2 on
t1.id= t2.id
where t1.biling_profiles= #biling_profiles
I am trying to do a join between two tables but I am receiving this error
Ambiguous column name 'NurseWard'
Code:
select
#WardID = NurseWard
from
dbo.NurseTbl as o
inner join
inserted as i on o.NurseID = i.NurseID
This looks like the inserted table in a trigger. The inserted table has the same column names as the original table. From the linked article:
The inserted table stores copies of the affected rows during INSERT
and UPDATE statements. During an insert or update transaction, new
rows are added to both the inserted table and the trigger table. The
rows in the inserted table are copies of the new rows in the trigger
table.
The query has an alias on both the NurseTbl and inserted tables, and the inner join uses the aliases, but the select does not. You will need to add an alias to the NurseWard column in the select:
select #WardID = o.NurseWard -- or i.NurseWard depending on what you need
from dbo.NurseTbl as o
inner join inserted as i on
o.NurseID = i.NurseID
I have a question related to Netezza query performance .I have 2 tables Table A and Table B and Table B is the sub set of Table A with data alteration .I need to update those new values to table A from table B
We can have 2 approaches here
1) Left outer join and select relevant columns and insert in target table
2) Insert table a data into target table and update those values from tableB using join
I tried both and logically both are same.But Explain plan is giving different cost
for normal select
a)Sub-query Scan table "TM2" (cost=0.1..1480374.0 rows=8 width=4864 conf=100)
update
b)Hash Join (cost=356.5..424.5 rows=2158 width=27308 conf=21)
for left outer join
Sub-query Scan table "TM2" (cost=51.0..101474.8 rows=10000000 width=4864 conf=100)
From this I feel left outer join is better .Can anyone put some thought on this and guide
Thanks
The reason that the cost of insert into table_c select ... from table_a; update table_c set ... from table_b; is higher is because you're inserting, deleting, then inserting. Updates in Netezza mark the records to be updated as deleted, then inserts new rows with the updated values. Once the data is written to an extent, it's never (to my knowledge) altered.
With insert into table_c select ... from table_a join table_b using (...); you're only inserting once, thereby only updating all the zone maps once. The cost will be noticeably lower.
Netezza does an excellent job of keeping you away from the disk on reads, but it will write to the disk as often as you tell it to. In the case of updates, seemingly more so. Try to only write as often as is necessary to gain benefits of new distributions and co-located joins. Any more than that, and you're just using excess commit actions.
I want to join 2 tables using an Inner Join on 2 columns, both are of (nvarchar, null) type. The 2 columns have the same data in them, but the join condition is failing. I think it is due to the spaces contained in the column values.
I have tried LTRIM, RTRIM also
My query:
select
T1.Name1, T2.Name2
from
Table1 T1
Inner Join
Table2 on T1.Name1 = T2.Name2
I have also tried like this:
on LTRIM(RTRIM(T1.Name1)) = LTRIM(RTRIM(T2.Name2))
My data:
Table1 Table2
------ ------
Name1(Column) Name2(Column)
----- ------
Employee Data Employee Data
Customer Data Customer Data
When I check My data in 2 tables with
select T1.Name1,len(T1.Name1)as Length1,Datalength(T1.Name1)as DataLenght1 from Table1 T1
select T2.Name2,len(T2.Name2)as Length2,Datalength(T2.Name2)as DataLenght2 from Table2 T2
The result is different Length and DataLength Values for the 2 tables,They are not same for 2 tables.
I can't change the original data in the 2 tables. How can I fix this issue.
Thank You
Joins do not have special rules for equality. The equality operator always works the same way. So if a = b then the join on a = b would work. Therefore, a <> b.
Check the contents of those fields. They will not be the same although you think they are:
select convert(varbinary(max), myCol) from T
Unicode has invisible characters (that only ever seem to cause trouble).
declare #t table (name varchar(20))
insert into #t(name)values ('Employee Data'),('Customer Data')
declare #tt table (name varchar(20))
insert into #tt(name)values ('EmployeeData'),('CustomerData')
select t.name,tt.name from #t t
INNER JOIN #tt tt
ON RTRIM(LTRIM(REPLACE(t.name,' ',''))) = RTRIM(LTRIM(REPLACE(tt.name,' ','')))
I would follow the following schema
Create a new table to store all the possible names
Add needed keys and indexes
Populate with existing names
Add columns to your existing tables to store the index of the name
Create relative foreign keys
Populate the new columns with correct indexes
Create procedure to perform an insert in new tables names only in case the value is not existing
Perform the join using the new indexes
I have two tables, each with some columns that are the same. However, each table also contains data that is unique. (Similar data includes a row name).
What I need to do is tack on the data from table two to it's matching row in table one (matching the name column).
Is there any way to do this?
I need stuff from table two to go into table 1 where the names match:
The following query should return all matching rows with columns from both tables. Note that any unique rows (that only exist in table one or two) will be excluded.
SELECT
one.matchingColum,
one.oddColum,
two.evenColumn
FROM one
JOIN two on one.matchingColumn = two.matchingColumn
If the data types are the same, then you can do a union
SELECT *
FROM table1
UNION
SELECT *
FROM table2
If the datatypes are not the same and you have a field that you can JOIN on, then you can do a JOIN
SELECT *
FROM table1 t1
LEFT JOIN table2 t2
ON t1.id = t2.id