How can I perform a select operation on two fields and view them as a single field?
ex:
I have a customer table that holds the customers data, I want to select both last_name and first_name (two different fields) and want to view them like this, "last_name, first_name"
using the oracle command not using any language.
SELECT last_name || ', ' || first_name full_name
FROM tbl
Try this -
SELECT '"' || last_name || ',' || first_name || '"' from table
Related
I've got procedure which works for too long period of time.
It parses query to arrays and then search for intersections with objects in database.
In first temp table I split every statement to array.
Second is about combine all possible database objects in array
Third - I'm looking for intersections in arrays.
Now this procedure uses 3 month time period for analyzing.
I dont want to reduce time. Maybe I will if
you dont suggest me something.
I've read that index GIN on array may help. What do you think?
Maybe you did it another way?
database - POSTGRES 11
CREATE TEMP TABLE temp_array_data
AS
(
SELECT id,
pid,
regexp_split_to_array(query, '\s+') as query
FROM t_stat_session
WHERE query_start::DATE BETWEEN pdtQueryDateFrom AND pdtQueryDateTo
AND duration IS NOT NULL
);
CREATE TEMP TABLE temp_sys_objects_data
AS
(
SELECT string_to_array(schemaname || '.' || tablename, '.') object_arr1,
string_to_array(schemaname || '.' || tablename, ',') object_arr2,
schemaname,
tablename object_name,
'T' AS object_type
FROM pg_catalog.pg_tables
UNION ALL
SELECT string_to_array(schemaname || '.' || viewname, '.') object_arr1,
string_to_array(schemaname || '.' || viewname, ',') object_arr2,
schemaname,
viewname object_name,
'VW' AS object_type
FROM pg_catalog.pg_views
UNION ALL
SELECT string_to_array(schemaname || '.' || matviewname, '.') object_arr1,
string_to_array(schemaname || '.' || matviewname, ',') object_arr2,
schemaname,
matviewname object_name,
'MVW' AS object_type
FROM pg_catalog.pg_matviews
);
CREATE TEMP TABLE temp_data_for_final
AS
(
SELECT id,
pid,
schemaname,
object_name,
object_type,
1 cnt
FROM temp_array_data adta,
temp_sys_objects_data
WHERE (ARRAY [object_arr1] && ARRAY [query] OR ARRAY [object_arr2] <# ARRAY [query])
);
I wanted to compare the two tables employees and employees_a and find the missing columns in the table comployees_a.
select a.Column_name,
From User_tab_columns a
LEFT JOIN User_tab_columns b
ON upper(a.table_name) = upper(b.table_name)||'_A'
AND a.column_name = b.column_name
Where upper(a.Table_name) = 'EMPLOYEES'
AND upper(b.table_name) = 'EMPLOYEES_A'
AND b.column_name is NULL
;
But this doesnt seems to be working. No rows are returned.
My employees table has the below columns
emp_name
emp_id
base_location
department
current_location
salary
manager
employees_a table has below columns
emp_name
emp_id
base_location
department
current_location
I want to find the rest two columns and add them into employees_a table.
I have more than 50 tables like this to compare them and find the missing column and add those columns into their respective "_a" table.
Missing columns? Why not using the MINUS set operator, seems to be way simpler, e.g.
select column_name from user_tables where table_name = 'EMP_1'
minus
select column_name from user_tables where table_name = 'EMP_2'
Thirstly, check if user_tab_columns table contains columns of your tables (in my case user_tab_columns is empty and I have to use all_tab_columns):
select a.Column_name
From User_tab_columns a
Where upper(a.Table_name) = 'EMPLOYEES'
Secondly, remove line AND upper(b.table_name) = 'EMPLOYEES_A', because upper(b.table_name) is null in case a column is not found. You have b.table_name in JOIN part of the SELECT already.
select a.Column_name
From User_tab_columns a
LEFT JOIN User_tab_columns b
ON upper(a.table_name) = upper(b.table_name)||'_A'
AND a.column_name = b.column_name
Where upper(a.Table_name) = 'EMPLOYEES'
AND b.column_name is NULL
You do not need any joins and can use:
select 'ALTER TABLE EMPLOYEES_A ADD "'
|| Column_name || '" '
|| CASE MAX(data_type)
WHEN 'NUMBER'
THEN 'NUMBER(' || MAX(data_precision) || ',' || MAX(data_scale) || ')'
WHEN 'VARCHAR2'
THEN 'VARCHAR2(' || MAX(data_length) || ')'
END
AS sql
From User_tab_columns
Where Table_name IN ('EMPLOYEES', 'EMPLOYEES_A')
GROUP BY COLUMN_NAME
HAVING COUNT(CASE table_name WHEN 'EMPLOYEES' THEN 1 END) = 1
AND COUNT(CASE table_name WHEN 'EMPLOYEES_A' THEN 1 END) = 0;
Or, for multiple tables:
select 'ALTER TABLE ' || MAX(table_name) || '_A ADD "'
|| Column_name || '" '
|| CASE MAX(data_type)
WHEN 'NUMBER'
THEN 'NUMBER(' || MAX(data_precision) || ',' || MAX(data_scale) || ')'
WHEN 'VARCHAR2'
THEN 'VARCHAR2(' || MAX(data_length) || ')'
END
AS sql
From User_tab_columns
Where Table_name IN ('EMPLOYEES', 'EMPLOYEES_A', 'SOMETHING', 'SOMETHING_A')
GROUP BY
CASE
WHEN table_name LIKE '%_A'
THEN SUBSTR(table_name, 1, LENGTH(table_name) - 2)
ELSE table_name
END,
COLUMN_NAME
HAVING COUNT(CASE WHEN table_name NOT LIKE '%_A' THEN 1 END) = 1
AND COUNT(CASE WHEN table_name LIKE '%_A' THEN 1 END) = 0;
fiddle
I have a PostgreSQL database with about 500 tables. Each table has a unique ID column named id and a user ID column named user_id. I would like to perform a full-text search of all varchar columns across all of these tables for a particular user. I do this today with ElasticSearch but I'd like to simplify my architecture. I understand that I can add full text search columns to all of the tables with things like stored generated columns and then add indices for fast full text search:
ALTER TABLE pgweb
ADD COLUMN textsearchable_index_col tsvector
GENERATED ALWAYS AS (to_tsvector('english', coalesce(title, '') || ' ' || coalesce(body, ''))) STORED;
CREATE INDEX textsearch_idx ON pgweb USING GIN (textsearchable_index_col);
However, I'm not familiar with how to do cross-table searches efficiently. Maybe a view across all textsearchable_index_col columns? I'd like the result to be something like the table name and id of the matching row. For example:
table_name | id
-------------+-------
table1 | 492
table42 | 20
If it matters, I'm using Ruby on Rails as the client with ActiveRecord. I'm using a managed PostgreSQL 13 database at Digital Ocean so I won't be able to install custom psql plugins.
Maybe It is not the answer you are looking for, because I am not sure if there is a better approach, but first I will try to automate the process.
I will make two dynamic queries, the first one to create columns textsearchable_index_col (in each table with at least one varchar column) and the other to create an index on that columns (one index per table).
You could ADD a textsearchable_index_col column for each "character varying" column instead only one concatenating all "character varying" columns, but in this case I will create one textsearchable_index_col column per table like you propose.
I assume table schema "public" but you can use the real one.
-- Create columns textsearchable_index_col:
SELECT 'ALTER TABLE ' || table_schema || '.' || table_name || E' ADD COLUMN textsearchable_index_col tsvector GENERATED ALWAYS AS (to_tsvector(\'english\', coalesce(' ||
string_agg(column_name, E', \'\') || \' \' || coalesce(') || E', \'\'))) STORED;'
FROM information_schema.columns
WHERE table_schema = 'public' AND data_type IN ('character varying')
GROUP BY table_schema, table_name;
-- Create indexes on textsearchable_index_col columns:
SELECT 'CREATE INDEX ' || table_name || '_textsearch_idx ON ' || table_schema || '.' || table_name || ' USING GIN (textsearchable_index_col);'
FROM information_schema.columns
WHERE table_schema = 'public' AND data_type IN ('character varying')
GROUP BY table_schema, table_name;
Then I will use a dynamic query to create a query (using UNION) to search on all that textsearchable_index_col columns:
You need to replace question mark by parameters (user_id and searched text), and take out the last "UNION ALL"
SELECT E'SELECT \'' || table_name || E'\' AS table_name, id FROM ' || table_schema || '.' || table_name || E' WHERE user_id = ? AND textsearchable_index_col' || ' ## to_tsquery(?) UNION ALL'
FROM information_schema.columns
WHERE table_schema = 'public' AND data_type IN ('character varying')
GROUP BY table_schema, table_name;
I'm trying to query using ILIKE on a user's name in PostgreSQL. There are columns for first_name and last_name, and I'd like the search term to match against the two concatenated, with a space between, so that a user may search for either, or a full name using one input. "John" "Doe" or "John Doe".
This always returns no results:
SELECT * FROM user_profiles WHERE first_name || ' ' || last_name ILIKE '%ryan%'
This always returns the one result I am expecting:
SELECT * FROM user_profiles WHERE first_name ILIKE '%ryan%'
Based on everything I've read, the first query should work as I am expecting, but it doesn't. No results and no errors. What am I missing here?
The first query would return no results if last_name were NULL (and similarly if first_name were NULL).
So, try this instead:
WHERE first_name || ' ' || COALESCE(last_name, '') ILIKE '%ryan%'
or:
WHERE CONCAT_WS(' ', first_name, last_name) ILIKE '%ryan%'
The concat_ws() function ignores arguments that are not NULL (except for the first argument).
Database is called 'school'. 'school' has tables with 'classroom_names' i.e 'room1' as a table, 'room2' as another table, etc. and each 'classroom_names' has a 'student_name' column.
I want to select all 'classroom_names' where it has a 'student_name' called 'John'.
So far I can only select all 'classroom_names' from the database like his:
select * from syscat.tables
I'd suggest the following. (Which tries to fix some of the problems with your design)
Create the following View
CREATE OR REPLACE VIEW SCHOOL.STUDENT_LIST AS
SELECT 'Room1' as CLASSROOM, student_name FROM SCHOOL.Room1
UNION ALL
SELECT 'Room2' as CLASSROOM, student_name FROM SCHOOL.Room2
UNION ALL
SELECT 'Room3' as CLASSROOM, student_name FROM SCHOOL.Room3
UNION ALL
SELECT 'Room4' as CLASSROOM, student_name FROM SCHOOL.Room4
UNION ALL
-- etc
SELECT 'RoomN' as CLASSROOM, student_name FROM SCHOOL.RoomN
Now you can say
SELECT CLASSROOM FROM STUDENT_LIST WHERE student_name = 'John'
You can built a dynamic query from the DB2 catalog
db2 "select 'select ' || trim(tabname) || ' classroom, student_name from '
|| tabname || ' where student_name = ''John'';'
from syscat.tables
where tabname like 'room%'" | db2 +p -tv
The last part (db2 +p -tv) allows to execute the output. If it does not work (buffer size), just remove this, and copy paste the output.