Is there a way to select from multiple tables using regexp in postgres or any SQL platform?
I want to select data from all tables in the database provided the table names follow a pattern.
I attempted the following but without any success...
SELECT cpu_id,date,time,duration,state,speed
FROM like 'count%' ","where date = '2012-09-27'
The table names are count1, count2 and so on. I want to take all of them.
I am sorry, I do not know how to put a reproducible example/data in this case.
There is no way to do that. Tables are meant to hold different rows and data. Have you considered merging the tables (instead, place some sort of index instead of different table names)?
Related
I'm attempting to combine two tables, both of which aren't related in any way except for a few columns (ID, Created Date, Country, etc.). In essence, I simply want to append one table to another. However, I would like to combine the columns that are similar and add on the columns that are not similar. I've attempted a Union, but my tables don't have the same number of columns. Currently, I'm working with this:
SELECT * FROM `leads`, `opportunity`
where `leads`.`Id` = `opportunity`.`Id`
which doesn't really work when I want to use this new query as a subquery elsewhere. Additionally, the fields in each table can change at any time, so I’m never sure which columns are matching or non-matching. I simply want to append the rows from one table onto the other while automatically combining columns with identical names. I feel like I'm missing something obvious...
NOTE: I am doing this within DOMO, so I have a few more limitations than I normally would.
You can use joins
SELECT * FROM `leads` JOIN `opportunity`
on `leads`.`Id` = `opportunity`.`Id`
and to get only selected columns
SELECT leads.column_name, opportunity.column_name FROM `leads` JOIN `opportunity`
on `leads`.`Id` = `opportunity`.`Id`
I have the following tables:
In table 2 (yellow looking fields), the first field is part of the following:
name1 RECORD NULLABLE
name1. name2 RECORD REPEATED
name1.name2. date_inserted TIMESTAMP NULLABLE
As you can see the last (sub-row?) of the row 25 is greyed because it is part of the repeated record name1.name2
I am trying to join table 2, with table 1(orange looking fields) on another field. I have 0 experience with records or repeated records but using FLATTEN() I managed to join them.
The problem is, I noticed that some dates from the 2nd after the join return NULL although there aren't any NULLS before it. So since I can't figure out what the greyed cells are I guess I am doing something wrong.
All this sums up to: How can I totally flatten all tables that I want to use so that there won't be any records at all and so I can go through the data with simple SQL statements? Please provide an example as well. Looking for something generic.
How can I totally flatten all tables that I want to use so that there won't be any records at all and so I can go through the data with simple SQL statements?
It really depends on the schemas you are working with. You can preprocess them, flatten the arrays and rename the structs fields, then use that as your base table to work with simple SQL statements
For your scenario, you can start by flattening the table 2, name2 column like this
SELECT
name2.date_inserted -- Add additional fields you want on the result
FROM table2, table2.name1.name2
You can do CROSS JOIN and LEFT JOIN to further adjust your results.
Please provide an example as well. Looking for something generic.
I'm not sure about a generic approach, since each schema would probably have distinct requirements. The key concept is to know how to flatten arrays and how to query struct with arrays and arrays of structs
You can find plenty examples in that documentation
How to select only specific number of columns from a table in hive. For Example, If I have Table with 50 Columns, then how Can I just select first 25 columns ? Is there any easy way to do it rather than hard coading the column names.
I guess that you're asking about using the order in which you defined your columns in your CREATE TABLE statement. No, that's not possible in Hive for the moment.
You could do the trick by adding a new column COLUMN_NUMBER and use that in your WHERE statements, but in that case I would really think twice of the trade off between spending some more time typing your queries and messing your whole table design by adding unnecessary columns. Apart from the fact that if you need to change your table schema in the future (for instance, by adding a new column), adapting your previous code with different column numbers would be painful.
im planning to build a new ads system and we are considering to use google bigquery.
ill quickly describe my data flow :
Each User will be able to create multiple ADS. (1 user, N ads)
i would like to store the ADS impressions and i thought of 2 options.
1- create a table for impressions , for example table name is :Impressions fields : (userid,adsid,datetime,meta data fields...)
in this options of all my impressions will be stored in a single table.
main pros : ill be able to big data queries quite easily.
main cons: table will be hugh, and with multiple queries, ill end up paying too much (:
option 2 is to create table per ads
for example, ads id 1 will create
Impression_1 with fields (datetime,meta data fields)
pros: query are cheaper, data table is smaller
cons: todo big dataquery sometimes ill have to create a union and things will complex
i wonder what are your thoughts regarding this ?
In BigQuery it's easy to do this, because you can create tables per each day, and you have the possibility to query only those tables.
And you have Table wildcard functions, which are a cost-effective way to query data from a specific set of tables. When you use a table wildcard function, BigQuery only accesses and charges you for tables that match the wildcard. Table wildcard functions are specified in the query's FROM clause.
Assuming you have some tables like:
mydata.people20140325
mydata.people20140326
mydata.people20140327
You can query like:
SELECT
name
FROM
(TABLE_DATE_RANGE(mydata.people,
TIMESTAMP('2014-03-25'),
TIMESTAMP('2014-03-27')))
WHERE
age >= 35
Also there are Table Decorators:
Table decorators support relative and absolute <time> values. Relative values are indicated by a negative number, and absolute values are indicated by a positive number.
To get a snapshot of the table at one hour ago:
SELECT COUNT(*) FROM [data-sensing-lab:gartner.seattle#-3600000]
There is also TABLE_QUERY, which you can use for more complex queries.
I need to compare the two table data with in one database.match the data using some columns form table.
Stored this extra rows data into another table called "relationaldata".
while I am searched ,found some solutin.
But it's not working to me
http://weblogs.sqlteam.com/jeffs/archive/2004/11/10/2737.aspx
can any one help how to do this.
How compare two table data with in one database using redgate(Tool)?
Red Gate SQL Data Compare lets you map together two tables in the same database, provided the columns are compatible datatypes. You just put the same database in the source and target, then go to the Object Mapping tab, unmap the two tables, and map them together.
Data Compare used to use UNION ALL, but it was filling up tempdb, which is what will happen if the table has a high row count. It does all the "joins" on local hard disk now using a data cache.
I think you can use Except clause in sql server
INSERT INTO tableC
(
Col1
, col2
, col3
)
select Col1,col2,col3from tableA
Except
select Col1,col2,col3 from tableB
Please refer for more information
http://blog.sqlauthority.com/2008/08/07/sql-server-except-clause-in-sql-server-is-similar-to-minus-clause-in-oracle/
Hope this helps