I have a below SP which has sql query which need to refactor db2 query,in db2 i dont know how to concatenate the flag condition remaining query to main query.
CREATE PROCEDURE EMPLOYEE
(IN EMPID varchar(1000),
IN BFLAG char(3))
RESULT SETS 1
LANGUAGE SQL
P1: BEGIN
SET v_sql = 'select c.id,c.name from emp c'
IF BFLAG <> 'T' THEN
SET v_sql = v_sql ||
' left outer join dept U
where c.empid in (' || EMPID || ') ';
ELSE
SET v_sql = v_sql ||
' where c.empid in (' || EMPID || ') ';
END IF;
how to concatenate query in db2 based on flag value specified above condition.
DECLARE c_id CURSOR WITH RETURN FOR
select c.id,c.name from emp c;
Too many errors.
You should study how the compound-statement must be constructed.
Every variable must be declared.
The order of statements inside is significant: variable declarations first, then statements, cursors. SQL-procedure-statements are afterwards only.
You get erroneous dynamic statement if BFLAG <> 'T' is true: left join without conditions.
If the questions is how to use cursor with dynamic statements, then here is an example:
CREATE PROCEDURE TEST_DYNAMIC (IN P_REST varchar(1000))
DYNAMIC RESULT SETS 1
LANGUAGE SQL
P1: BEGIN
DECLARE v_sql VARCHAR (1000);
DECLARE v_s STATEMENT;
DECLARE v_c1 CURSOR WITH RETURN FOR v_s;
SET v_sql = 'select ' || P_REST;
PREPARE v_s FROM v_sql;
OPEN v_c1;
END
#
CALL TEST_DYNAMIC (' * FROM EMPLOYEE WHERE EMPNO IN (''000010'', ''000020'')')#
If not, then try to compile your routine without errors at least and show the runtime error / unexpected result if any...
Related
I am trying to write a plpgsql procedure to perform spatial tiling of a postGIS table. I can perform the operation successfully using the following procedure in which the table names are hardcoded. The procedure loops through the tiles in tile_table and for each tile clips the area_table and inserts it into split_table.
CREATE OR REPLACE PROCEDURE splitbytile()
AS $$
DECLARE
tile RECORD;
BEGIN
FOR tile IN
SELECT tid, geom FROM test_tiles ORDER BY tid
LOOP
INSERT INTO split_table (id, areaname, ttid, geom)
SELECT id, areaname, tile.tid,
CASE WHEN st_within(base.geom, tile.geom) THEN st_multi(base.geom)
ELSE st_multi(st_intersection(base.geom, tile.geom)) END as geom
FROM area_table as base
WHERE st_intersects(base.geom, tile.geom);
COMMIT;
END LOOP;
END;
$$ LANGUAGE 'plpgsql';
Having tested this successfully, now I need to convert it to a dynamic procedure where I can provide the table names as parameters. I tried the following partial conversion, using format() for inside of loop:
CREATE OR REPLACE PROCEDURE splitbytile(in_table text, grid_table text, split_table text)
AS $$
DECLARE
tile RECORD;
BEGIN
FOR tile IN
EXECUTE format('SELECT tid, geom FROM %I ORDER BY tid', grid_table)
LOOP
EXECUTE
FORMAT(
'INSERT INTO %1$I (id, areaname, ttid, geom)
SELECT id, areaname, tile.tid,
CASE WHEN st_within(base.geom, tile.geom) THEN st_multi(base.geom)
ELSE st_multi(st_intersection(base.geom, tile.geom)) END as geom
FROM %2$I as base
WHERE st_intersects(base.geom, tile.geom)', split_table, in_table
);
COMMIT;
END LOOP;
END;
$$ LANGUAGE 'plpgsql';
But it throws an error
missing FROM-clause entry for table "tile"
So, how can I convert the procedure to a dynamic one? More specifically, how can I use the record data type (tile) returned by the for loop inside the loop? Note that it works when format is not used.
You can use EXECUTE ... USING to supply parameters to a dynamic query:
EXECUTE
format(
'SELECT r FROM %I WHERE c = $1.val',
table_name
)
INTO result_var
USING record_var;
The first argument to USING will be used for $1, the second for $2 and so on.
See the documentation for details.
Personally I use somehow different way to create dynamic functions. By concatination and execute function. You can also do like this.
CREATE OR REPLACE FUNCTION splitbytile()
RETURNS void AS $$
declare
result1 text;
table_name text := 'test_tiles';
msi text := '+7 9912 231';
msi text := 'Hello world';
code text := 'code_name';
_operator_id integer := 2;
begin
query1 := 'SELECT msisdn from ' || table_name || ' where msisdn = ''' || msi::text ||''';';
query2 := 'INSERT INTO ' || table_name || '(msisdn,usage,body,pr_code,status,sent_date,code_type,operator_id)
VALUES( ''' || msi::text || ''',' || true || ',''' || _body::text || ''',''' || code::text || ''',' || false || ',''' || time_now || ''',' || kod_type || ',' || _operator_id ||');';
execute query1 into result1;
execute query2;
END;
$function$
You just make your query as text then anywhere you want you can execute it. Maybe by checking result1 value inside If statement or smth like that.
Is it possible to iterate over a table's records and make a left join with them in a stored procedure?
Something like this:
FOR r IN SELECT tablename FROM tablewithtablenames ORDER BY tablename ASC
LOOP
INSERT INTO temp_Results
SELECT
temp_ids.Key as Key,
loggedvalue.pk_timestamp,
FROM
(temp_idS AS temp_ids
LEFT JOIN
quote_ident(r.tablename) AS loggedvalue
ON temp_ids.Key = loggedvalue.pk_fk_id);
END LOOP;
Unfortunately i get the following error message when i want to execute the stored procedure. (Function creation was successful.)
Error message:
ERROR: column loggedvalue.pk_fk_id does not exist LINE 29:
ON temp_ids.Key = "loggedvalue...
I have the feeling that i convert the record in a wrong way maybe because when i manually replaced the quote_ident(r.tablename) to the name of the table that i know the r contains it was fine, also i traced out the r.tablename in the loop and it was correct also.
As a_horse_with_no_name pointed out i should have use dynamic sql because in plpgsql you can not use a variable as a table name so i eliminated the loop and i used a union all:
CREATE OR REPLACE FUNCTION getaffectedtables(
OUT tableNames TEXT)
as $$
BEGIN
SELECT TRIM(TRAILING ' UNION ALL ' FROM string_agg('','SELECT * FROM "' || "tablename" || '" UNION ALL '))
INTO tableNames
FROM exampleTable;
END;$$
LANGUAGE plpgsql;
Then i used dynamic execute:
DECLARE
affectednames TEXT;
BEGIN
affectednames := getaffectedtables();
EXECUTE '
SELECT
temp_ids.Key as Key,
loggedvalue.pk_timestamp,
FROM
(temp_idS AS temp_ids
LEFT JOIN
('|| affectednames ||') AS loggedvalue
ON temp_ids.Key = loggedvalue.pk_fk_id);';
My company is going to start generating documents using data from our database and I am designing the function that will spit out the document text. These documents will need to contain data taken from multiple tables, with hundreds of columns and invariably some records will be missing data.
I am trying to make a function that will take null fields and replace them with a little error message that makes it clear to the end user that a piece of data is missing. Since the end user is totally unfamiliar with the backend, I want these messages to reference something intelligible to them.
My solution is pretty simple yet I for the life of me can't get it to work. The record identifier, table name are set as parameters in the function. The function then loops through names for each of the columns in the specified table, building a query that contains a bunch of case statements. Once the loop is complete, the identifier is appended and then the query is executed, returning the results to the calling function.
Despite reading around quite a bit, the best I can is a single column/row containing all the results - not useful to me at all, because I need to be able to easily reference specific pieces of data in the parent query. I am a beginner with Postgres and the documentation is too complex for me to understand, any help would be appreciated.
-- Function: data_handler(text, text)
-- DROP FUNCTION data_handler(text, text);
CREATE OR REPLACE FUNCTION data_handler(target_uri text, target_table TEXT)
RETURNS SETOF record AS
$BODY$
DECLARE
c text;
strSQL text;
site_only text;
result record;
BEGIN
--We need the schema for strSQL but the loop needs just the table name.
site_only = split_part(target_table, '.', 2);
FOR c IN
SELECT column_name
FROM information_schema.columns
WHERE table_name = site_only
LOOP
strSQL = concat(strSQL, chr(10), '(SELECT CASE WHEN ', c::text, '::text IS NULL THEN concat(', chr(39), '<Error:', chr(39), ', (SELECT lkp_value FROM alb_cr.lkp_field_values WHERE column_name = ', chr(39), c::text, chr(39), ')::text, ', chr(39), ' value not found>', chr(39), ')::text ELSE ',
c::text, '::text END AS ', c::text, '_convert) AS ', c::text, ',');
END LOOP;
strSQL = LEFT(strSQL, character_length(strSQL) - 1);
strSQL = concat('SELECT ', strSQL, ' FROM ', target_table, ' WHERE nm_site_id = ', chr(39), target_uri, chr(39));
RETURN QUERY EXECUTE strSQL;
RAISE NOTICE 'strSQL: %', strSQL;
--RETURN strSQL;
--RETURN QUERY EXECUTE format('SELECT ' || strSQL || 'FROM %s WHERE nm_site_id = $1', pg_typeof(target_table)) USING target_uri;
END
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION data_handler(text, text)
OWNER TO inti;
You could create views for that as well, in the following example on a schema nullsbegone:
-- create the schema to hold the views
create schema if not exists nullsbegone;
-- create a function to create the views (any and all that you might need)
create or replace function nullsbegone.f_make_view_of(p_tablename text) returns void as $f$
begin
execute ($$
create or replace view nullsbegone.$$||(select relname from pg_class where oid = $1::regclass)||$$
returns void as
select $$||array_to_string(array(
select case when not attnotnull then 'COALESCE('||quote_ident(attname)||$$::text, (SELECT '<Error:'''||lkp_value||''' value not found>' FROM alb_cr.lkp_field_values
WHERE column_name = $$||quote_literal(attname)||$$)) AS $$
else '' end || quote_ident(attname)
from pg_attribute
where attrelid = $1::regclass and attnum > 0 order by attnum
), E', \n')||$$
from $$||$1);
end;$f$ language plpgsql;
-- create the view based on a given table
select nullsbegone.f_make_view_of('yourschema.yourtable');
-- select from your view as if you were selecting from the actual table
select * from nullsbegone.yourtable
where nm_site_id = 'yoursite';
I have a database with multiple identical schemas. There is a number of tables all named 'tran_...' in each schema. I want to loop through all 'tran_' tables in all schemas and pull out records that fall within a specific date range. This is the code I have so far:
CREATE OR REPLACE FUNCTION public."configChanges"(starttime timestamp, endtime timestamp)
RETURNS SETOF character varying AS
$BODY$DECLARE
tbl_row RECORD;
tbl_name VARCHAR(50);
tran_row RECORD;
out_record VARCHAR(200);
BEGIN
FOR tbl_row IN
SELECT * FROM pg_tables WHERE schemaname LIKE 'ivr%' AND tablename LIKE 'tran_%'
LOOP
tbl_name := tbl_row.schemaname || '.' || tbl_row.tablename;
FOR tran_row IN
SELECT * FROM tbl_name
WHERE ch_edit_date >= starttime AND ch_edit_date <= endtime
LOOP
out_record := tbl_name || ' ' || tran_row.ch_field_name;
RETURN NEXT out_record;
END LOOP;
END LOOP;
RETURN;
END;
$BODY$
LANGUAGE plpgsql;
When I attempt to run this, I get:
ERROR: relation "tbl_name" does not exist
LINE 1: SELECT * FROM tbl_name WHERE ch_edit_date >= starttime AND c...
#Pavel already provided a fix for your basic error.
However, since your tbl_name is actually schema-qualified (two separate identifiers in : schema.table), it cannot be escaped as a whole with %I in format(). You have to escape each identifier individually.
Aside from that, I suggest a different approach. The outer loop is necessary, but the inner loop can be replaced with a simpler and more efficient set-based approach:
CREATE OR REPLACE FUNCTION public.config_changes(_start timestamp, _end timestamp)
RETURNS SETOF text AS
$func$
DECLARE
_tbl text;
BEGIN
FOR _tbl IN
SELECT quote_ident(schemaname) || '.' || quote_ident(tablename)
FROM pg_tables
WHERE schemaname LIKE 'ivr%'
AND tablename LIKE 'tran_%'
LOOP
RETURN QUERY EXECUTE format (
$$
SELECT %1$L || ' ' || ch_field_name
FROM %1$s
WHERE ch_edit_date BETWEEN $1 AND $2
$$, _tbl
)
USING _start, _end;
END LOOP;
RETURN;
END
$func$ LANGUAGE plpgsql;
You have to use dynamic SQL to parametrize identifiers (or code), like #Pavel already told you. With RETURN QUERY EXECUTE you can return the result of a dynamic query directly. Examples:
Return SETOF rows from PostgreSQL function
Refactor a PL/pgSQL function to return the output of various SELECT queries
Remember that identifiers have to be treated as unsafe user input in dynamic SQL and must always be sanitized to avoid syntax errors and SQL injection:
Table name as a PostgreSQL function parameter
Note how I escape table and schema separately:
quote_ident(schemaname) || '.' || quote_ident(tablename)
Consequently I just use %s to insert the already escaped table name in the later query. And %L to escape it a string literal for output.
I like to prepend parameter and variable names with _ to avoid naming conflicts with column names. No other special meaning.
There is a slight difference compared to your original function. This one returns an escaped identifier (double-quoted only where necessary) as table name, e.g.:
"WeIRD name"
instead of
WeIRD name
Much simpler yet
If possible, use inheritance to obviate the need for above function altogether. Complete example:
Select (retrieve) all records from multiple schemas using Postgres
You cannot use a plpgsql variable as SQL table name or SQL column name. In this case you have to use dynamic SQL:
FOR tran_row IN
EXECUTE format('SELECT * FROM %I
WHERE ch_edit_date >= starttime AND ch_edit_date <= endtime', tbl_name)
LOOP
out_record := tbl_name || ' ' || tran_row.ch_field_name;
RETURN NEXT out_record;
END LOOP;
I'm trying to write a function in PL/PgSQL that have to work with a table it receives as a parameter.
I use EXECUTE..INTO..USING statements within the function definition to build dynamic queries (it's the only way I know to do this) but ... I encountered a problem with RECORD data types.
Let's consider the follow (extremely simplified) example.
-- A table with some values.
DROP TABLE IF EXISTS table1;
CREATE TABLE table1 (
code INT,
descr TEXT
);
INSERT INTO table1 VALUES ('1','a');
INSERT INTO table1 VALUES ('2','b');
-- The function code.
DROP FUNCTION IF EXISTS foo (TEXT);
CREATE FUNCTION foo (tbl_name TEXT) RETURNS VOID AS $$
DECLARE
r RECORD;
d TEXT;
BEGIN
FOR r IN
EXECUTE 'SELECT * FROM ' || tbl_name
LOOP
--SELECT r.descr INTO d; --IT WORK
EXECUTE 'SELECT ($1)' || '.descr' INTO d USING r; --IT DOES NOT WORK
RAISE NOTICE '%', d;
END LOOP;
END;
$$ LANGUAGE plpgsql STRICT;
-- Call foo function on table1
SELECT foo('table1');
It output the following error:
ERROR: could not identify column "descr" in record data type
although the syntax I used seems valid to me. I can't use the static select (commented in the example) because I want to dinamically refer the columns names.
So..someone know what's wrong with the above code?
It's true. You cannot to use type record outside PL/pgSQL space.
RECORD value is valid only in plpgsql.
you can do
EXECUTE 'SELECT $1.descr' INTO d USING r::text::xx;
$1 should be inside the || ,like || $1 || and give spaces properly then it will work.
BEGIN
EXECUTE ' delete from ' || quote_ident($1) || ' where condition ';
END;