sql declare cursor

A cursor (cursor) is a database query stored on a DBMS server that is not a SELECT statement, but rather a result set that is retrieved by the statement. After the cursor is stored, the application can scroll or browse the data as needed. Using cursors Steps to use cursors: Before you use a cursor, you must

Original: http://ntk2006.blog.sohu.com/135331235.html Cursor ConceptCursors provide a flexible way to retrieve and operate data from tables. cursors are mainly used on servers to process SQL statements sent from clients to servers, or data processing requests in batch processing, stored procedures, and triggers. The advantage of a cursor is that it can locate a

emp_sal_cursor % found loop-- Judge the employee's salary and perform the update operation-- Dbms_output.put_line (v_id | ':' | v_sal );If v_sal Temp: = 0.05;Elsif Vanderbilt Sal Temp: = 0.03;Elsif Vanderbilt Sal Temp: = 0.02;ElseTemp: = 0.01;End if;-- Dbms_output.put_line (v_id | ':' | v_sal | ',' | temp );Update employees set salary = salary * (1 + temp) where employee_id = v_id;Fetch emp_sal_cursor into v_sal, v_id;End loop;-- Close the cursorClose emp_sal_cursor;End; Use the decode function

table, essentially, a cursor is essentially a mechanism for extracting one record at a time from a result set that includes multiple data records. Cursors are always associated with an SQL query statement because the cursor consists of a result set (which can be 0, one, or multiple records retrieved by a related selection statement) and a

Document directory Lifecycle 2.8. DECLARE statement Both SQL server and mysql are our frequently used database systems. Next we will introduce the differences between the values of SQL server and mysql variables, and hope to enlighten you. Variables in SQL server must be affirmed first and then assigned values: Th

confusingDeclareType T is table of Tt2%rowtype;V_tab T;BeginSELECT * Bulk collect into V_tab--* changed to field will be errorFrom TT2;For I in 1.. V_tab.count-2 Loop-minus 2 here because the last 2 numbers don't have to be judged, or the loop will get an error.If V_tab (i+2). Id-v_tab (i). id = 2 and V_tab (i+2). Name = V_tab (i). Name ThenDbms_output.put_line (V_tab (i). name| | ' -' | | V_tab (i). ID);Dbms_output.put_line (V_tab (i+1). name| | ' -' | | V_tab (i+1). ID);Dbms_output.put_line (

area char (%) DECLARE @ contributor number of users CHAR ( declare @sql char) declare cur_data cursor for select CONVERT (varchar (10), due time,) as Expiration time, Slices, count (distinct main_id) as number of users from V_aipu_fee where commit time >=convert (varc

Label:--Maintenance Database-- -- cursors (cursor)-- -- Overview : Note: The result set for querying results using a SELECT statement is a whole, and cursors can provide this processing mechanism if you want to work with one row or branch of data at a time. cursors can be understood as pointers . Which record the pointer points to, and which record is the action record . How the cursor han

SQL reads a table set with a cursor, and SQL reads the set with a cursor GoDeclare @ auid uniqueidentifier, @ name varchar (Max) --- define the variable Declare auth_cur cursor for -- defines the

-- Declare Declare a variable using the declare statement in the body of a batch or process and assign a value to it using the set or select statement. The cursor variable can be declared through this statement and can be used in other statements related to the cursor. All v

Label:1. Cursors are useful when the data table has no ID (identity), but the cursor eats more memory, reduces available concurrency, consumes bandwidth, locks resources, and, of course, more code 2. If you can not use cursors, try to avoid using cursors, run out and then must be closed and released, try not to define the cursor on a large amount of data, try not to use the

is not a unique row identifier, the dynamic cursor is converted to a keyset cursor. If the keyset cursor cannot be opened, it is converted to an insensitive cursor. The same is true for a cursor defined using the SQL ANSI-92 synt

Tags: User bar implicit conversion first location assignment set size getWhat is a cursor The result set, which is the collection of all row data returned after the select query. Cursors are a mechanism for working with result sets, which can locate a row in the result set, read or write multiple data, or move the cursor to navigate to the rows you want to manipulate the data. Generally complex stored proce

If object_id ('tempdb .. # temp1010') is not nullDrop table # temp1010GoIf object_id ('tempdb .. # temp2020') is not nullDrop table # temp2020GoCreate Table # temp2020 (It_id nvarchar (100) null);Insert # temp2020 (it_id) values (1)Insert # temp2020 (it_id) values (2)Insert # temp2020 (it_id) values (3)Create Table # temp1010 (It_id nvarchar (100) null,Pc_total nvarchar (100) null,Note_total nvarchar (100) null);Declare@ It_id nvarchar (100 ),@ Pc_tot