Hello I am using Redshift where I have a staging table & a base table. one of the column (city) in my base table has data type varchar & its length is 100.When I am trying to insert the column value from staging table to base table, I want this value to be truncated to 1st 100 characters or leftmost 100 characters. Can this be possible in Redshift?
INSERT into base_table(org_city) select substring(city,0,100) from staging_table;
I tried using the above query but it failed. Any solutions please ?
Try this! Your base table column length is Varchar(100), so you need to substring 0-99 chars, which is 100 chars. You are trying to substring 101 chars.
INSERT into base_table(org_city) select substring(city,0,99) from staging_table;
Related
I'm trying to do get a tall table (with just 3 columns indicating variable, timestamp and value) into a wide format where timestamp is the index, the columns are the variable names, and the values are the values of the new table.
In python/pandas this would be something along the lines of
import pandas as pd
df = pd.read_csv("./mydata.csv") # assume timestamp, varname & value columns
df.pivot(index="timestamp", columns="varname", values="value")
for PostgreSQL there exists crosstab, so far I have:
SELECT * FROM crosstab(
$$
SELECT
"timestamp",
"varname",
"value"
FROM mydata
ORDER BY "timestamp" ASC, "varname" ASC
$$
) AS ct(
"timestamp" timestamp,
"varname1" numeric,
...
"varnameN" numeric
);
The problem is that I can potentially have dozens to hundreds of variable names. The types are always numeric, number of variable names is not stable (we could need more variables or realize that others are not necessary).
Is there a way to automate the "ct" part so that some other query (e.g. select distinct "varname" from mydata) produces it instead of me having to type in every single variable name present?
PS: PSQL version is 12.9 at home, 14.0 in production. Number of rows in the original table is around 2 million, however I'm going to filter by timestamp and varname, so potentially only a few hundreds of thousands rows. After filtering I got ~50 unique varnames, but that will increase in a few weeks.
Background:
I am making a db for a reservartions calendar. The reservations are hourly based, so I need to insert many items to one column called "hours_reserved".
Example tables of what I need:
Table "Space"
Column / Values
id / 1
date / 5.2.2020
hours / { 8-10, 10-12 }
Table "reservation"
Column / Values
id / 1
space_id / 1
date / 5.2.2020
reserved_hours / 8-10
Table "reservation"
Column / Values
id / 2
space_id / 1
date / 5.2.2020
hours / 10-12
So I need to have multiple items inserted into "space" table "hours" column.
How do I do this in Postgres?
Also is there a better way to accomplish this?
There is more way to do this, depending on the type of the hours field (i.e. text[], json or jsonb) I'd go with jsonb just because you can do a lot of things with it and you'll find this experience to be useful in the short term.
CREATE TABLE "public"."space"
("id" SERIAL, "date_schedule" date, "hours" jsonb, PRIMARY KEY ("id"))
Whenever you insert a record in this table that's manually crafted, write it as text (single quoted json object) and cast it to jsonb
insert into "space"
(date_schedule,hours)
values
('05-02-2020'::date, '["8-10", "10-12"]'::jsonb);
There is more than one way to match these available hours against the reservations and you can take a look at the docs, on the json and jsonb operations. For example, doing:
SELECT id,date_schedule, jsonb_array_elements(hours) hours FROM "public"."space"
would yield
Which has these ugly double quotes (which is correct, since json can hold several kinds of scalars, that column is polimorfic :D)
However, you can perform a little transformation to remove them and be able to perform a join with reservations
with unnested as (
SELECT id,date_schedule, jsonb_array_elements(hours) hours FROM "public"."space"
)
select id,date_schedule,replace(hours::text, '"','') from unnested
The same can be achieved defining the field as text[] (the insertion syntax is different but trivial)
in that scenario your data will look like:
Which you can unwrap as:
SELECT id,date_schedule, unnest(hours) FROM "public"."space"
Apparently
ALTER TABLE mytable
ADD COLUMN myarray text[];
Works fine.
I got a following problem when trying to put(update) into that column using postman(create works fine):
{
"myarray": ["8-10"]
}
Results into:
"message": "error: invalid input syntax for type integer:
\"{\"myarray\":[\"8-10\"]}\""
I need to create a table in hive to insert a data like the one below:
Column 1 -- account id String(11 characters)
Column 2 -- Age int
Column 3 -- duplicate account_id
The data is stored in a text file delimited by spaces, but the last column will have multiple values, hence doing querying I will need to eliminate that row if the value is present in that column
Example text file:
Thomsxx3125 25 Davidxx3125 Raghuxx3125 Vijayxx3125 Gracexx3125
Appreciate your help on this please.
You can't create duplicate column names.
Here is a query that will work:
create table if not exists name_of_table
(
account_id string comment '11 characters',
age int,
account_id2 string
)
fields terminated by ' '
stored as textfile;
You can also refer to the official documentation for Hive:
https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-CreateTable
I have a column in redshift database which contains values like 11E, 11N, 11W,12W,12E,12S,1S,2E. Need to sort column like 1S,2E,11E,11N,11W,12E,12S,12W.
you need to separate the numbers from the characters.
try this order
SELECT a FROM example
ORDER BY
convert(integer,case when length(a)= 2 then left(a,1) else left(a,2) end),
right(a,1)
My table looks like below,
Table Name: Number_List
Columns Name: Num_ID INTEGER
First_Number VARCHAR(16)
Last_Number VARCHAR(16)
In that, Num_ID is PK. and the rest of the columns First_Number and Last_Number always have a 8 digit number.
my requirement is to update that column to 6 Digit entry..
Consider the Entries in the two columns are 32659814 (First_Number) and 32659819 (Last_Number). Now I need to write a update query to change the entries in the table to 326598 (First_Number) and 326598 (Last_Number).
and this table has 15K entries and i need to update the whole in single query in single execution.
Please help me to resolve this.
TIA.
All you need is SUBSTR:
UPDATE SESSION.NUMBER_LIST
SET FIRST_NUMBER = SUBSTR(FIRST_NUMBER, 1,6)
,LAST_NUMBER = SUBSTR(LAST_NUMBER, 1,6)