How to use the cursor into a hand in memsql? - singlestore

Question

Hi Team how can we use cursor memsql,i did not saw any code using the cursor process in memesql procedure.
is there any other process to use cursor usage?

Answer 1

SingleStore DB (formerly known as MemSQL), has a COLLECT function where you can achieve read-only cursor functionality by calling COLLECT and iterating over the values in the resulting array. The array may be processed forwards, backwards or in an arbitrary order.
We have several use cases with sample SQL queries in our official documentation. I have included the first below as a reference:
Example 1: Using COLLECT with Static Queries
In the following example, COLLECT uses a query type variable, whose definition SELECT * from t is static.
DROP DATABASE IF EXISTS memsql_docs_example;
CREATE DATABASE memsql_docs_example;
USE memsql_docs_example;
CREATE TABLE t(id INT, name TEXT);
CREATE TABLE output_log(msg TEXT);
INSERT INTO t VALUES (1, 'red'), (2, 'green'), (3, 'blue');
DELIMITER //
CREATE OR REPLACE PROCEDURE p() AS
DECLARE
qry QUERY(id INT, name TEXT) = SELECT id, name FROM t;
arr ARRAY(RECORD(id INT, name TEXT));
_id INT;
_name TEXT;
BEGIN
arr = COLLECT(qry);
FOR x in arr LOOP
_id = x.id;
_name = x.name;
INSERT INTO output_log VALUES(CONCAT('[', _id, ', ', _name, ']'));
END LOOP;
END //
DELIMITER ;
CALL p();
SELECT * FROM output_log ORDER BY msg;
Cheers!
David, Education Delivery Specialist #
SingleStore DB (formerly MemSQL)