Just a misapplied abstraction it seems to me. A db cursor is an abstraction, meant for data set traversal. From Wikipedia article on subject: In computer science and technology, a database cursor is a control structure that enables traversal over the records in a database. Cursors facilitate subsequent processing in conjunction with the traversal, such … Read more
I think you can do what you want with DBMS_SQL package. You can also check these: Using Dynamic SQL COLUMN_VALUE Procedure For example: declare TYPE curtype IS REF CURSOR; src_cur curtype; curid NUMBER; namevar VARCHAR2(50); numvar NUMBER; datevar DATE; desctab DBMS_SQL.DESC_TAB; colcnt NUMBER; dsql varchar2(1000) := ‘select card_no from card_table where rownum = 1’; begin … Read more
1. Implicit cursor It’s almost always better to use the implicit cursor of a FOR loop than to resort to a somewhat slower and unwieldy explicit cursor. I have written thousands of PL/pgSQL functions and only a hand full of times explicit cursors made any sense. CREATE OR REPLACE FUNCTION avoidable_states() RETURNS SETOF varchar LANGUAGE … Read more
A cursor will only accept a select statement, so if the SQL really needs to be dynamic make the declare cursor part of the statement you are executing. For the below to work your server will have to be using global cursors. Declare @UserID varchar(100) declare @sqlstatement nvarchar(4000) –move declare cursor into sql to be … Read more
You can read large blobs in pieces. First find out which ones need this treatment: SELECT id, length(blobcolumn) FROM mytable WHERE length(blobcolumn) > 1000000 and then read chunks with substr: SELECT substr(blobcolumn, 1, 1000000) FROM mytable WHERE id = 123 SELECT substr(blobcolumn, 1000001, 1000000) FROM mytable WHERE id = 123 … You could also compile … Read more
Here’s a comparison between toArray() and cursors after a find() in the Node.js MongoDB driver. Common code: var MongoClient = require(‘mongodb’).MongoClient, assert = require(‘assert’); MongoClient.connect(‘mongodb://localhost:27017/crunchbase’, function (err, db) { assert.equal(err, null); console.log(‘Successfully connected to MongoDB.’); const query = { category_code: “biotech” }; // toArray() vs. cursor code goes here }); Here’s the toArray() code that … Read more
The docs for SQLiteDatabase.query() say that the query methods return: “A Cursor object, which is positioned before the first entry.” Calling moveToFirst() does two things: it allows you to test whether the query returned an empty set (by testing the return value) and it moves the cursor to the first result (when the set is … Read more
If you are using the default cursor, a MySQLdb.cursors.Cursor, the entire result set will be stored on the client side (i.e. in a Python list) by the time the cursor.execute() is completed. Therefore, even if you use for row in cursor: you will not be getting any reduction in memory footprint. The entire result set … Read more
Note: This code is untested Define a record for your refCursor return type, call it rec. For example: TYPE MyRec IS RECORD (col1 VARCHAR2(10), col2 VARCHAR2(20), …); –define the record rec MyRec; — instantiate the record Once you have the refcursor returned from your procedure, you can add the following code where your comments are … Read more
Using cursors compared to big resultsets is like using video streaming instead of downloading an video in one swoop, and watching it when it has downloaded. If you download, you have to have a few gigs of space and the patience to wait until the download finished. Now, no matter how fast your machine or … Read more