CREATE OR REPLACE FUNCTION foo(_t regclass) RETURNS void LANGUAGE plpgsql AS $func$ BEGIN EXECUTE 'ALTER TABLE ' || _t || ' ADD COLUMN c1 varchar(20) , ADD COLUMN c2 varchar(20)'; END $func$; Call: SELECT foo('table_name'); Or: SELECT foo('my_schema.table_name'::regclass); To define a function that returns a table, you use the following form of the create function statement: create or replace function function_name ( parameter_list ) returns table ( column_list ) language plpgsql as $$ declare -- variable declaration begin -- body end; $$. The properties work as follows: PASS_THROUGH determines whether a column appears in the output. film if the title matches with this pattern. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. postgresql - tg_table_schema - INSERT with dynamic table name in trigger function tg_table_name (2) clear chan , Return dynamic columns of a temporary table. Copyright © 1996-2020 The PostgreSQL Global Development Group, CAPXS+azwjF3-5E_kPj3GtZJvhZE_nqMRF7XA8UZZFXn_UX=+QA@mail.gmail.com, Re: Return dynamic columns of a temporary table, Re: pg_upgrade default ports in the --help output. postgresql> CREATE EXTENSION IF NOT EXISTS tablefunc; Let’s say you have the following table. Copying Types variable%TYPE %TYPE provides the data type of a variable or table column. In the function, we return a query that is a result of a SELECT statement. crosstab(text) crosstab(text sql) crosstab(text sql, int N) The crosstab function is used to produce … PostgreSQL also provides a built-in Crosstab function that allows you to easily create pivot table in PostgreSQL. What i have been trying to do is to ... somehow return a temporary table with dynamic columns. Hi, i am new to postresql and have been trying to convert some of our mssqlprocedures into postresql functions. The IN keyword. ; Dynamic refers to constantly changing. Hello. To avoid spending my life typing out column names, I wrote a function in Postgres procedural language ( PL/pgSQL ) that will generate a crosstab query automatically. create or replace function function1(column_name varchar,relation_name anyelement) returns setof anyelement as $fun$ declare cname varchar; add_column varchar; group_column varchar; select_query varchar; begin if column_name='fname' then cname:=quote_ident(column_name); … Columns returned by table functions may be included in SELECT, JOIN, or WHERE clauses in the same manner as a table, view, or subselect column. The variable always has a particular data-type give to it like boolean, text, char, integer, double precision, date, time, etc. In some cases, one needs to perform operations at the database object level, such as tables, indexes, columns, roles, and so on. I am trying to create crosstab queries in PostgreSQL such that it automatically generates the crosstab columns instead of hardcoding it. ; Dynamic Partitioning thus refers to automatically splitting a large table into smaller tables. Each column is separated by a comma (,). I have written a function that dynamically generates the column list that I need for my crosstab query. Lines 10–15 of the describe function remove any of the table’s columns that are in the hide_cols list. I would like to do something like CREATE OR REPLACE FUNCTION add_column(name, anyelement) RETURNS … The following is the result: Notice that if you call the function using the following statement: PostgreSQL returns a table with one column that holds the array of films. The execution continues and the result set is building up in each iteration of the loop. You can use this to declare variables that will hold database values. Before we get started, here’s a few basic terms. Please use ide.geeksforgeeks.org, generate link and share the link here. As a side-effect you get a temp table to keep results for the duration of the session - like you needed in your last question. create table table1 ( slno integer, fname varchar, lname varchar, city varchar, country varchar ) --Function. Introduction to PostgreSQL Variables. 39.3.3. See your article appearing on the GeeksforGeeks main page and help other Geeks. Basically, the column which is to be converted from rows into columns. Is it possible? Because the data type of release_yearof the film table is not an integer, we have to convert it into an integer using CAST. ; Now that we’re on the same page, let’s go more in depth on how we can achieve dynamic partitioning with PostgreSQL! Another way, similar to what I proposed to your previous question: Return a set of well known type. EXCEPTION or CREATE TEMP TABLE IF NOT EXISTS? user_id users.user_id%TYPE; For example, let's say you have a column named user_id in your users table. The idea is to substitute the result of this function in the crosstab query using dynamic sql.. Please write to us at contribute@geeksforgeeks.org to report any issue with the above content. For example, to analyze the car_portal_appschema tables, one could write the following script: In person table: person_ctime and person_mtime In item table item_ctime and item_mtime Firstly, the reason I have column names based on table name and not use generic names such as "ctime" or "mtime" is because I create a view that joins these tables (plus other tables) and the view requires that I have distinct names. I use a language plpgsql with return next table function, whose return table has just a single, varchar, column, in the “Pretty printed ad hoc reports for administrators” use case described in my third post. The return type can be a base, composite, or domain type, or can reference the type of a table column. By using our site, you In the function, we return a query that is a result of a SELECT statement. create function GetEmployees() returns setof employee as 'select * from employee;' language 'sql'; This very simple function simply returns all the rows from employee. In practice, you often process each individual row before appending it in the function’s result set. The code sets the PASS_THROUGH and FOR_READ properties of the table’s columns. The second parameter is the release year of the film. Some basic definitions. To adjust the values in columns like GDP or Dividends, you may automate this with a dynamic UPDATE similarly to the CREATE TABLE, if the columns that need the updates exist under identical names in all these tables (but that seems unlikely except if the schema was … Depending on the implementation language it might also be allowed to specify "pseudotypes" such as cstring. We will use the film table in the sample database for the demonstration: The following function returns all films whose titles match a particular pattern using ILIKE operator: This get_film(varchar) function accepts one parameter p_pattern which is a pattern that you want to match with the film title. The IN keyword, as already explained above, lists all the distinct values from the pivot column that we want to add to the pivot table column list. If a table function returns a base data type, the single result column is named for the function. To declare a variable with the same data type as users.user_id you write:. Create Pivot Table in PostgreSQL using Crosstab function. Is it possible? However, you need to install the table_func extension to enable Crosstab function. Next we ‘DECLARE’ the variables for use within our function. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, PostgreSQL - Create Auto-increment Column using SERIAL, Creating a REST API Backend using Node.js, Express and Postgres, PostgreSQL - Introduction to Stored Procedures, PostgreSQL - Connect To PostgreSQL Database Server in Python, PostgreSQL - Insert Data Into a Table using Python, PostgreSQL - Connecting to the database using Python, Write Interview The following example illustrates the idea. Postgresql function return table with dynamic columns Return dynamic table with unknown columns from PL/pgSQL function, This is hard to solve, because SQL demands to know the return type at call time. Our function takes two arguments, an employee and a car id, both being integers. In a prior article Use of Out and InOut Parameters we demonstrated how to use OUT parameters and INOUT parameters to return a set of records from a PostgreSQL function. Re: What's faster? pgsql-general(at)postgresql(dot)org: Subject: Return dynamic columns of a temporary table: Date: 2012-10-04 12:00:31: Message-ID: ... procedures into postresql functions. If the function is not supposed to return a value, specify void as the return type. We can test the function using the following statement: We called the get_film(varchar) function to get all films whose title starts with Al. This operator tells the pivot operator on which column do we need to apply the pivot function. To return a table from the function, you use RETURNS TABLE syntax and specify the columns of the table. First let's look at a simple SQL function that returns an existing table's rowtype. The following function returns all films whose titles match a particular pattern using, function to get all films whose title starts with, We have created a function with the similar name. In this case all rows of the last query's result are returned. In this article, we will look into the process of developing functions that returns a table. They are used like a table, view, or subselect in the FROM clause of a query. There is another approach to doing this, and that is to use the ANSI Standard RETURNS TABLE construct. Partitioning refers to splitting a large table into smaller tables. Since your column list is dynamic, create a temporary table for the purpose. Notice that the columns in the SELECT statement must match with the columns of the table that we want to return. The PostgreSQL variable is a convenient name or an abstract name given to the memory location. We have created a function with the similar name get_film(varchar, int) but accepts two parameters: The RETURN NEXT statement adds a row to the result set of the function. Alternatively, an SQL function can be declared to return a set, by specifying the function's return type as SETOF sometype, or equivalently by declaring it as RETURNS TABLE (columns). Further details appear below. Writing code in comment? We use cookies to ensure you have the best browsing experience on our website. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Experience. This is called a pivot table and can be achieved in PostgreSQL using the crosstab() function, but there’s a catch: you need to type out all of the column names. passing column name to a PL/pgsql function for ALTER TABLE ADD. There, many of the rows (like headings and rule-offs) are produced each with its own dedicated return next statement. SRFs can return either a rowtype as defined by an existing table or a generic record type. I want to have a pivot like function in which i should have variable number of columns.i went for crosstab but it doesnot support variable number of columns.Can any body suggest an alternative.like if i have a event at a particular time of the day like one at 02:35,11:34, then i should have column … Is it possible? For example, a database developer would like to vacuum and analyze a specific schema object, which is a common task after the deployment in order to update the statistics. Each column is separated by a comma (, ). Notice that the columns in the SELECT statement must match with the columns of the table that we want to return. To return a table from the function, you use RETURNS TABLE syntax and specify the columns of the table. If you come from a SQL Server or IBM DB2 background, the RETURNS TABLE construct is probably most familiar, but still … What i have been trying to do is tosomehow return a temporary table with dynamic columns. Our function returns a ‘SETOF sales’; which means we’re returning a set of the type ‘sales’, every table in PostgreSQL is a composite type consisting of the types of it’s individual columns. This announces the type to the system. Sets the PASS_THROUGH and FOR_READ properties of the table have the following.. Idea is to be converted from rows into columns help other Geeks the hide_cols list clicking on the `` article! The code sets the PASS_THROUGH and FOR_READ properties of the film table is not an integer using CAST using sql. Takes two arguments, an employee and a car id, both being integers since your column list is,! Converted from rows into columns look into the process of developing functions that RETURNS an existing 's! Browsing experience on our website function takes two arguments, an employee a! Given to the memory location each column is named for the function is not supposed to return a table... Each iteration of the loop specify `` pseudotypes '' such as cstring will hold database values 's say you the... And help other Geeks a few basic terms for use within our.! The second parameter is the release year of the table that we want return! Postgresql also provides a built-in crosstab function that allows you to easily create table! Pivot operator on which column do we need to install the table_func extension to enable crosstab function into an using! Each column is named for the purpose that is a result of variable. We use cookies to ensure you have the best browsing experience on our.... For the purpose table1 ( slno integer, fname varchar, country varchar ) function... Value, specify void as the return type column is named for the function a column named user_id in users... The pivot function with dynamic columns each iteration of the table ’ s say you have the table... Each individual row before appending it in the function the film if the function, we return a temporary with! Basic terms named user_id in your users table column named user_id in users! Or an abstract name given to the memory location a result of a SELECT statement, many of table. Tosomehow return a table from the function, you use RETURNS table syntax and the... Data type as users.user_id you write: own dedicated return next statement function remove any the. Any issue with the columns of the film to ensure you have column. Operator on which column do we need to apply the pivot operator on which column do need. Which column do we need to install the table_func extension to enable crosstab function that dynamically generates column! As the return type incorrect by clicking on the implementation language it also! What i have been trying to do is tosomehow return a value specify. 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To substitute the result of a SELECT statement must match with the same data type, the single column! @ geeksforgeeks.org to report any issue with the above content next we ‘ declare ’ variables...