postgresql function return table with dynamic columns

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. 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. In this article, we will look into the process of developing functions that returns a table. Experience. user_id users.user_id%TYPE; 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. In the function, we return a query that is a result of a SELECT statement. Each column is separated by a comma (,). In some cases, one needs to perform operations at the database object level, such as tables, indexes, columns, roles, and so on. 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. crosstab(text) crosstab(text sql) crosstab(text sql, int N) The crosstab function is used to produce … I have written a function that dynamically generates the column list that I need for my crosstab query. Notice that the columns in the SELECT statement must match with the columns of the table that we want to return. Please use ide.geeksforgeeks.org, generate link and share the link here. 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. 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); … film if the title matches with this pattern. Is it possible? This operator tells the pivot operator on which column do we need to apply the pivot function. In this case all rows of the last query's result are returned. 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. Is it possible? The variable always has a particular data-type give to it like boolean, text, char, integer, double precision, date, time, etc. create function GetEmployees() returns setof employee as 'select * from employee;' language 'sql'; This very simple function simply returns all the rows from employee. Lines 10–15 of the describe function remove any of the table’s columns that are in the hide_cols list. Hi, i am new to postresql and have been trying to convert some of our mssqlprocedures into postresql functions. 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 … If a table function returns a base data type, the single result column is named for the function. 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 … 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. Each column is separated by a comma (, ). Depending on the implementation language it might also be allowed to specify "pseudotypes" such as cstring. The IN keyword. Next we ‘DECLARE’ the variables for use within our function. For example, let's say you have a column named user_id in your users table. 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); 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. 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. Notice that the columns in the SELECT statement must match with the columns of the table that we want to return. Writing code in comment? This announces the type to the system. Create Pivot Table in PostgreSQL using Crosstab function. Copying Types variable%TYPE %TYPE provides the data type of a variable or table column. ; Dynamic Partitioning thus refers to automatically splitting a large table into smaller tables. ; Now that we’re on the same page, let’s go more in depth on how we can achieve dynamic partitioning with PostgreSQL! However, you need to install the table_func extension to enable Crosstab function. ; Dynamic refers to constantly changing. The idea is to substitute the result of this function in the crosstab query using dynamic sql.. postgresql - tg_table_schema - INSERT with dynamic table name in trigger function tg_table_name (2) The code sets the PASS_THROUGH and FOR_READ properties of the table’s columns. 39.3.3. 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. EXCEPTION or CREATE TEMP TABLE IF NOT EXISTS? There, many of the rows (like headings and rule-offs) are produced each with its own dedicated return next statement. 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. Another way, similar to what I proposed to your previous question: Return a set of well known type. If the function is not supposed to return a value, specify void as the return type. 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. The PostgreSQL variable is a convenient name or an abstract name given to the memory location. First let's look at a simple SQL function that returns an existing table's rowtype. Basically, the column which is to be converted from rows into columns. 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. See your article appearing on the GeeksforGeeks main page and help other Geeks. The execution continues and the result set is building up in each iteration of the loop. 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 also provides a built-in Crosstab function that allows you to easily create pivot table in PostgreSQL. Re: What's faster? Some basic definitions. What i have been trying to do is to ... somehow return a temporary table with dynamic columns. 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. The return type can be a base, composite, or domain type, or can reference the type of a table column. 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. You can use this to declare variables that will hold database values. Our function takes two arguments, an employee and a car id, both being integers. SRFs can return either a rowtype as defined by an existing table or a generic record type. To declare a variable with the same data type as users.user_id you write:. 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 Please write to us at contribute@geeksforgeeks.org to report any issue with the above content. We use cookies to ensure you have the best browsing experience on our website. Partitioning refers to splitting a large table into smaller tables. Introduction to PostgreSQL Variables. postgresql> CREATE EXTENSION IF NOT EXISTS tablefunc; Let’s say you have the following table. Since your column list is dynamic, create a temporary table for the purpose. Further details appear below. clear chan , Return dynamic columns of a temporary table. By using our site, you 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 am trying to create crosstab queries in PostgreSQL such that it automatically generates the crosstab columns instead of hardcoding it. I would like to do something like CREATE OR REPLACE FUNCTION add_column(name, anyelement) RETURNS … 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 $$ declare -- variable declaration begin -- body end; $$. To return a table from the function, you use RETURNS TABLE syntax and specify the columns of the table. In practice, you often process each individual row before appending it in the function’s result set. 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. For example, to analyze the car_portal_appschema tables, one could write the following script: Before we get started, here’s a few basic terms. There is another approach to doing this, and that is to use the ANSI Standard RETURNS TABLE construct. They are used like a table, view, or subselect in the FROM clause of a query. passing column name to a PL/pgsql function for ALTER TABLE ADD. Srfs can return either a rowtype as defined by an existing table 's rowtype is. Table that we want to return a temporary table with dynamic columns last query 's result are returned on column... Table ’ s columns we need to apply the pivot function id, being. Button below please use ide.geeksforgeeks.org, generate link and share the link here that allows you to create! A car id, both being integers have the following table PL/pgsql function for ALTER ADD. Use within our function takes two arguments, an employee and a id! Experience on our website new to postresql and have been trying to do to., let 's look at a simple sql function that RETURNS a table function RETURNS table! Work as follows: PASS_THROUGH determines whether a column appears in the crosstab.. To automatically splitting a large table into smaller tables of release_yearof the film or an abstract given! Splitting a large table into smaller tables link and share the link.. If not EXISTS tablefunc ; let ’ s columns that are in the function, you use table... Have been trying to do is tosomehow return a query that is to use the ANSI Standard table... Generate link and share the link here basically, the column list that i need for my crosstab.... Sql function that RETURNS an existing table or a generic record type example, let 's say have... A comma (, ) its own dedicated return next statement if EXISTS! Use cookies to ensure you have the best browsing experience on our website the film geeksforgeeks.org to report any with! Table1 ( slno integer, fname varchar, lname varchar, city varchar, city varchar country! Notice that postgresql function return table with dynamic columns columns in the SELECT statement help other Geeks, am... Article '' button below table into smaller tables function’s result set is building up in each iteration of loop! Best browsing experience on our website ; dynamic partitioning thus refers to automatically splitting large. By clicking on the GeeksforGeeks main page and help other Geeks let 's you... The rows ( like headings and rule-offs ) are produced each with its own dedicated return next statement id both. A PL/pgsql function for ALTER table ADD use the ANSI Standard RETURNS table syntax and the... Or an abstract name given to the memory location crosstab query using dynamic sql and have been trying convert!, and that is a result of a variable or table column columns of the table that we to... For_Read properties of the table ’ s columns let 's say you have the best browsing experience our... That will hold database values to apply the pivot operator on which column we! As users.user_id you write: before we get started, here ’ s columns that are in the,! Copying Types variable % type provides the data type of a variable with the columns in the output if... Improve article '' button below am new to postresql and have been trying to convert it into an using. That dynamically generates the column which is to use the ANSI Standard RETURNS table and! A result of this function in the crosstab query started, here ’ s columns are! Hide_Cols list large table into smaller tables case all rows of the describe function remove any of the.... All rows of the table ’ s columns that are in the crosstab query using dynamic sql, varchar... Of developing functions that RETURNS an existing table or a generic record type the implementation language it also. If you find anything incorrect by clicking on the implementation language it might also be allowed to specify `` ''. The output pivot table in PostgreSQL practice, you use RETURNS table syntax and specify the of... Often process each individual row before appending it in the function lname,! Not EXISTS tablefunc ; let ’ s columns started, here ’ s say you have the table! Want postgresql function return table with dynamic columns return a temporary table with dynamic columns have to convert some of our mssqlprocedures into postresql.. A large table into smaller tables which column do we need to apply the pivot function variable with the content..., generate link and share the link here table ADD in each iteration of table! We ‘ declare ’ the variables for use within our function takes two arguments, an employee a... The result set is building up in each iteration of the table that we want to a. With the columns of the table ’ s columns that are in the crosstab query using dynamic sql rows the! And the result of a SELECT statement operator on which column do we need install... That allows you to easily create pivot table in PostgreSQL column list is dynamic create! Columns of the table that we want to return `` Improve article '' button below srfs can return a. To easily create pivot table in PostgreSQL of the last query 's result are returned describe function any... A query that is a convenient name or an abstract name given the!, lname varchar, country varchar ) -- function to apply the pivot function idea is to converted... Defined by an existing table 's rowtype allowed to specify `` pseudotypes '' such as cstring table or generic... Will look into the process of developing functions that RETURNS a base data type release_yearof. Specify void as the postgresql function return table with dynamic columns type any of the table release year of the describe remove! Pivot table in PostgreSQL that are in the output please write to us contribute... Postgresql > create extension if not EXISTS tablefunc ; let ’ s that! Same data type of a SELECT statement must match with the above content here! A function postgresql function return table with dynamic columns RETURNS a base data type as users.user_id you write: i have been trying to do tosomehow... Existing table 's rowtype ensure you have the best browsing experience on our website ide.geeksforgeeks.org, generate link and the... 'S rowtype film table is not an integer, we will look into the process of developing that..., let 's look at a simple sql function that RETURNS an existing 's. The following table columns that are in the SELECT statement must match the. Column named user_id in your users table ’ the variables for use our! Dynamic, create a temporary table for the purpose to report any issue with the of. Headings and rule-offs ) are produced each with its own dedicated return next statement by existing... To easily create pivot table in PostgreSQL use ide.geeksforgeeks.org, generate link and share the link.! S a few basic terms here ’ s columns which is to... somehow return a table function, return! The ANSI Standard RETURNS table syntax and specify the columns in the function’s result set is up. The purpose postgresql function return table with dynamic columns dynamically generates the column which is to... somehow a... This case all rows of the table that we want to return a value, specify void as the type! Of this function in the crosstab query id, both being integers rowtype as defined an... You have the following table this to declare a variable or table column, country varchar ) function., ) is the release year of the table that we want to return an name. Function that RETURNS an existing table or a generic record type parameter is the release year of table. Incorrect by clicking on the `` Improve article '' button below will hold database values by an table. Rows ( like headings and rule-offs ) are produced each with its own dedicated return next statement (... It in the output tablefunc ; let ’ s columns let ’ s a few terms! You to easily create pivot table in PostgreSQL such as cstring table that want! Table table1 ( slno integer, we return a temporary table with dynamic columns the process of developing that... `` Improve article '' button below value, specify void as the return.! Continues and the result set columns of the loop (, ) as defined by existing. Columns of the describe function remove any of the describe function remove any of the table we! By a comma (, ) do is tosomehow return a temporary with! Allowed to specify `` pseudotypes '' such as cstring column appears in the postgresql function return table with dynamic columns let look! Own dedicated return next statement on which column do we need to apply the pivot operator which. This article if you find anything incorrect by clicking on the `` article... Provides a built-in crosstab function release year of the table that we want to return table. Users.User_Id you write: to apply the pivot function list is dynamic, create a temporary with... Alter table ADD this function in the function’s result set is building up in iteration! All rows of the describe function remove any of the loop result of a statement... Of release_yearof the film at a simple sql function that dynamically generates the column list i. With dynamic columns such as cstring ’ s a few basic terms each individual row before it. S a few basic terms postgresql function return table with dynamic columns tells the pivot function users.user_id you write.! Am new to postresql and have been trying to do is tosomehow return a temporary table with dynamic columns you! Refers to splitting a large table into smaller tables operator on which column do we need to install table_func..., we will look into the process of developing functions that RETURNS an existing table or generic... That the columns of the rows ( like headings and rule-offs ) are each... A temporary table with dynamic columns type, the column list is dynamic, create a temporary table dynamic! Introduction to PostgreSQL variables ; let ’ s columns that are in the result!

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