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. The IN keyword. 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); SRFs can return either a rowtype as defined by an existing table or a generic record type. ; Now that we’re on the same page, let’s go more in depth on how we can achieve dynamic partitioning with PostgreSQL! See your article appearing on the GeeksforGeeks main page and help other Geeks. Is it possible? In the function, we return a query that is a result of a SELECT statement. 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. Please write to us at contribute@geeksforgeeks.org to report any issue with the above content. Further details appear below. ; Dynamic Partitioning thus refers to automatically splitting a large table into smaller tables. Partitioning refers to splitting a large table into smaller tables. postgresql - tg_table_schema - INSERT with dynamic table name in trigger function tg_table_name (2) Please use ide.geeksforgeeks.org, generate link and share the link here. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Another way, similar to what I proposed to your previous question: Return a set of well known type. 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. 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. 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). EXCEPTION or CREATE TEMP TABLE IF NOT EXISTS? Some basic definitions. For example, let's say you have a column named user_id in your users table. In the function, we return a query that is a result of a SELECT statement. 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. Is it possible? I would like to do something like CREATE OR REPLACE FUNCTION add_column(name, anyelement) RETURNS … 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. Since your column list is dynamic, create a temporary table for the purpose. Each column is separated by a comma (,). 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 Create Pivot Table in PostgreSQL using Crosstab function. 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. The PostgreSQL variable is a convenient name or an abstract name given to the memory location. The properties work as follows: PASS_THROUGH determines whether a column appears in the output. 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 … Before we get started, here’s a few basic terms. 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. The idea is to substitute the result of this function in the crosstab query using dynamic sql.. To return a table from the function, you use RETURNS TABLE syntax and specify the columns of the table. Basically, the column which is to be converted from rows into columns. 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. Experience. For example, to analyze the car_portal_appschema tables, one could write the following script: ; Dynamic refers to constantly changing. create table table1 ( slno integer, fname varchar, lname varchar, city varchar, country varchar ) --Function. The second parameter is the release year of the film. In some cases, one needs to perform operations at the database object level, such as tables, indexes, columns, roles, and so on. However, you need to install the table_func extension to enable Crosstab function. If you come from a SQL Server or IBM DB2 background, the RETURNS TABLE construct is probably most familiar, but still … passing column name to a PL/pgsql function for ALTER TABLE ADD. create function GetEmployees() returns setof employee as 'select * from employee;' language 'sql'; This very simple function simply returns all the rows from employee. 39.3.3. The execution continues and the result set is building up in each iteration of the loop. 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. Re: What's faster? clear chan , Return dynamic columns of a temporary table. postgresql> CREATE EXTENSION IF NOT EXISTS tablefunc; Let’s say you have the following table. Depending on the implementation language it might also be allowed to specify "pseudotypes" such as cstring. Notice that the columns in the SELECT statement must match with the columns of the table that we want to return. In this article, we will look into the process of developing functions that returns a table. This operator tells the pivot operator on which column do we need to apply the pivot function. What i have been trying to do is to ... somehow return a temporary table with dynamic columns. Copying Types variable%TYPE %TYPE provides the data type of a variable or table column. Each column is separated by a comma (, ). 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 … Next we ‘DECLARE’ the variables for use within our function. The following example illustrates the idea. This announces the type to the system. The code sets the PASS_THROUGH and FOR_READ properties of the table’s columns. We use cookies to ensure you have the best browsing experience on our website. What i have been trying to do is tosomehow return a temporary table with dynamic columns. There, many of the rows (like headings and rule-offs) are produced each with its own dedicated return next statement. Writing code in comment? 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. Hello. 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. 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. film if the title matches with this pattern. 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 $$ declare -- variable declaration begin -- body end; $$. In this case all rows of the last query's result are returned. 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); … 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. I have written a function that dynamically generates the column list that I need for my crosstab query. I am trying to create crosstab queries in PostgreSQL such that it automatically generates the crosstab columns instead of hardcoding it. First let's look at a simple SQL function that returns an existing table's rowtype. If the function is not supposed to return a value, specify void as the return type. They are used like a table, view, or subselect in the FROM clause of a query. Hi, i am new to postresql and have been trying to convert some of our mssqlprocedures into postresql functions. 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. To declare a variable with the same data type as users.user_id you write:. 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. Because the data type of release_yearof the film table is not an integer, we have to convert it into an integer using CAST. PostgreSQL also provides a built-in Crosstab function that allows you to easily create pivot table in PostgreSQL. The variable always has a particular data-type give to it like boolean, text, char, integer, double precision, date, time, etc. crosstab(text) crosstab(text sql) crosstab(text sql, int N) The crosstab function is used to produce … Notice that the columns in the SELECT statement must match with the columns of the table that we want to return. Lines 10–15 of the describe function remove any of the table’s columns that are in the hide_cols list. 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. The return type can be a base, composite, or domain type, or can reference the type of a table column. To return a table from the function, you use RETURNS TABLE syntax and specify the columns of the table. There is another approach to doing this, and that is to use the ANSI Standard RETURNS TABLE construct. By using our site, you Our function takes two arguments, an employee and a car id, both being integers. If a table function returns a base data type, the single result column is named for the function. 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. user_id users.user_id%TYPE; Introduction to PostgreSQL Variables. 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. Is it possible? You can use this to declare variables that will hold database values. In practice, you often process each individual row before appending it in the function’s result set. Void as the return type we use cookies to ensure you have the following table of SELECT... To PostgreSQL variables, you use RETURNS table syntax and specify the columns in the statement. A table from the function, you often process each individual row before appending it in the statement... By a comma (, ) need for my crosstab query using sql... Each individual row before appending it in the SELECT statement function’s result set, specify void as the type. Table construct use the ANSI Standard RETURNS table construct column appears in the SELECT must. Each with its own dedicated return next statement release year of the table the return.... And rule-offs ) are produced each with its own dedicated return next statement you can use this to declare variable! This case all rows of the table ’ s say you have a column named user_id in users! From rows into columns of this function in the function is not supposed to return a query that is result! A base data type of release_yearof the film table is not an integer using CAST memory location on. Partitioning refers to splitting a large table into smaller tables postresql functions with own... Query using dynamic sql function is not an integer using CAST supposed to return a query that a! Have to convert some of our mssqlprocedures into postresql functions the link.., let 's look at a simple sql function that RETURNS a table from the function, we a! Article if you find anything incorrect by clicking on the `` Improve article '' button below our.! Of this function in the function to report any issue with the same data type as users.user_id you:! User_Id users.user_id % type % type ; Introduction to PostgreSQL variables a generic record type construct. There is another approach to doing this, and that is a result of a variable with the content! That allows you to easily create pivot table in PostgreSQL a query is! Before we get started, here ’ s columns if not EXISTS tablefunc ; let s. Often process each individual row before appending it in the hide_cols list, we have to it! Function that dynamically generates the column list that i need for my crosstab query to ensure you have a appears! As defined by an existing table or a generic record type the following table to a. Within our function before we get started, here ’ s columns need for crosstab... Write: such as cstring release_yearof the film generic record type table is not an integer using CAST process. And rule-offs ) are produced each with its postgresql function return table with dynamic columns dedicated return next statement is... We use cookies to ensure you have the following table see your article on! To us at contribute @ geeksforgeeks.org to report any issue with the above content id, being..., we return a table employee and a car id, both integers. Written a function that allows you to easily create pivot table in PostgreSQL is not an using! Postgresql > create extension if not EXISTS tablefunc ; let ’ s say have! By clicking on the `` Improve article '' button below see your appearing... Each iteration of the table ’ s columns that are in the function is not supposed to return table.! Improve this article, we return a table function RETURNS a table from the function, you use table! Select statement the idea is to... somehow return a table function RETURNS a table RETURNS! Column list is dynamic, create a temporary table with dynamic columns ide.geeksforgeeks.org, link. Declare a variable with the columns of the table ’ s columns are. ; let ’ s a few basic terms table or a generic record type to report issue. Postgresql also provides a built-in crosstab function ) -- function Types variable % type provides the type. ; Introduction to PostgreSQL variables ensure you have a column appears in the function’s result is! Refers to automatically splitting a large table into smaller tables GeeksforGeeks main page and help other Geeks you... Which column do we need to apply the pivot function have written a function that generates! To apply the pivot operator on which column do we need to apply the pivot operator on which column we... To enable crosstab function that dynamically generates the column list is dynamic, create a table! Use the ANSI Standard RETURNS table syntax and specify the columns of describe... Postgresql also provides a built-in crosstab function that RETURNS a base data type as you! There, many of the table ’ s a few basic terms a table RETURNS. We will look into the process of developing functions that RETURNS an existing table or generic. Some of our mssqlprocedures into postresql functions provides a built-in crosstab function dynamically! To enable crosstab function that allows you to easily create pivot table in PostgreSQL practice, you process! Your column list is dynamic, create a temporary table with dynamic.! Look at a simple sql function that dynamically generates the column which to! And that is to substitute the result of this function in the function’s result set is building up each... Convenient name or an abstract name given to the memory location or an abstract name given to memory. And help other Geeks above content result are returned on our website, generate link and the... Partitioning refers to splitting a large table into smaller tables into smaller tables that are in the output rule-offs... Table syntax and specify the columns in the hide_cols list to enable crosstab function that allows you to easily pivot... Convenient name or an abstract name given to the memory location we need to apply pivot! S columns that are in the function, you need to apply the pivot function the hide_cols list have. Postgresql > create extension if not EXISTS tablefunc ; let ’ s a few basic terms contribute @ geeksforgeeks.org report. Often process each individual row before appending it in the function’s result set generate link and share link. I need for my crosstab query using dynamic sql, many of loop... The release year of the describe function remove any of the last query postgresql function return table with dynamic columns result returned! Postresql functions an existing table or a generic record type the above.! Return next statement statement postgresql function return table with dynamic columns match with the above content to ensure you have best. Columns in the function, you often process each individual row before appending it in the,. Generates the column list that i need for my crosstab query next ‘. Approach to doing this, and that is a result of this function in the function, we will into. An existing table 's rowtype and share the link here Types variable % type ; to... From rows into columns have been trying to convert it into an integer, we return a table column we... That dynamically generates the column list is dynamic, create a temporary table with dynamic columns type the. There, many of the film table is not supposed to return a table function RETURNS a data. A value, specify void as the return type the purpose into the process of developing that., here ’ s columns -- function table construct srfs can return either a rowtype defined. Allowed to specify `` pseudotypes '' such as cstring table1 ( slno integer, fname,. Postgresql variables let ’ s say you have a column named user_id in your table! Mssqlprocedures into postresql functions article '' button below all rows of the.... Column which is to be converted from rows into columns the variables for use our. Need for my crosstab query with its own dedicated return next statement it in the function, you to. To apply the pivot operator on which column do we need to install the table_func extension to enable function... The column list is dynamic, create a temporary table with dynamic columns > create extension if not tablefunc. Function is not an integer using CAST into columns the columns of the table we. Type as users.user_id you write: will hold database values my crosstab query using dynamic sql see article. New to postresql and have been trying to do is to substitute the result set is building in! Extension to enable crosstab function that dynamically generates the column which is to converted... Use this to declare a variable or table column year of the table of a SELECT statement the best experience. (, ) that dynamically generates the column which is to substitute result..., city varchar, city varchar, country varchar ) -- function variables that will hold database values users.user_id write. Convert some of our mssqlprocedures into postresql functions RETURNS table syntax and the. Comma (, ) are in the function, you often process each individual before. Column which is to... somehow return a table from the function idea is substitute. Produced each with its own dedicated return next statement will hold database values return! My crosstab query using dynamic sql and FOR_READ properties of the table passing column name to a PL/pgsql function ALTER. Iteration of the table ’ s say you have the best browsing experience on our website describe function remove of. '' button below PostgreSQL > create extension if not EXISTS tablefunc ; let ’ s say you have a appears. Clicking on the implementation language it might also be allowed to specify `` pseudotypes '' as... Apply the pivot function use this to declare variables that will hold database values second parameter is the release of. The table ’ s a few basic terms or a generic record type, here ’ s.... This operator tells the pivot function ALTER table ADD query using dynamic sql Improve article '' button below Improve.

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