free barcode generator source code in c#.net Fetching Rows from a Cursor Automatically in Font

Make PDF 417 in Font Fetching Rows from a Cursor Automatically

Fetching Rows from a Cursor Automatically
Creating PDF 417 In None
Using Barcode drawer for Font Control to generate, create PDF417 image in Font applications.
www.OnBarcode.com
Barcode Maker In None
Using Barcode generation for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Introducing, from the far away shores of Redwood Shores, California, the star of our show, the one, the only: the CURSOR FOR LOOP! Why all the fanfare you ask. It s because the CURSOR FOR LOOP is the heart and soul of PL/SQL s abilities. The CURSOR FOR LOOP allows you to work with a cursor that returns multiple rows, one row at a time, using a very nice and neat structure that does everything for you automatically. Listing 5-8 is a revision of Listing 5-1. The difference is that Listing 5-8 utilizes the automatic CURSOR FOR LOOP, instead of the manually coded loop involving OPEN, FETCH, and CLOSE. Listing 5-8. An Example of Using a CURSOR FOR LOOP, cursor_for_loop_the_doe_family.sql 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 rem rem rem rem rem cursor_for_loop_the_doe_family.sql by Donald J. Bales on 12/15/2006 An anonymous PL/SQL procedure to select the first names for the Doe family from the Worker table.
Paint UPC-A Supplement 2 In None
Using Barcode generation for Font Control to generate, create UPC Code image in Font applications.
www.OnBarcode.com
Code 39 Extended Creation In None
Using Barcode encoder for Font Control to generate, create ANSI/AIM Code 39 image in Font applications.
www.OnBarcode.com
set serveroutput on size 1000000; declare cursor c_worker( aiv_last_name in WORKER_T.last_name%TYPE) is select first_name from WORKER_T where last_name like aiv_last_name||'%' order by id; begin FOR r_worker IN c_worker('DOE') LOOP pl(r_worker.first_name); END LOOP; end; / The CURSOR FOR LOOP syntax used in Listing 5-8 is as follows:
Encode ANSI/AIM Code 128 In None
Using Barcode encoder for Font Control to generate, create Code 128 Code Set B image in Font applications.
www.OnBarcode.com
Printing QR Code In None
Using Barcode printer for Font Control to generate, create Denso QR Bar Code image in Font applications.
www.OnBarcode.com
FOR <record_name> IN <cursor_name> [(<cursor_parameters>)] LOOP -- Put your PL/SQL to be executed for each row here END LOOP; where <record_name> is the name of the record that will contain fields that correspond to columns in the associated cursor s SELECT statement; <cursor_name> is the name of the associated CURSOR; and <cursor_parameters> is a list of zero or more parameters to be passed to the CURSOR. The
Print Data Matrix ECC200 In None
Using Barcode creator for Font Control to generate, create Data Matrix image in Font applications.
www.OnBarcode.com
Ames Code Creation In None
Using Barcode maker for Font Control to generate, create Code-27 image in Font applications.
www.OnBarcode.com
CHAPTER 5 NEXT PLEASE, ONE ROW AT A TIME!
Generate PDF 417 In None
Using Barcode drawer for Microsoft Word Control to generate, create PDF-417 2d barcode image in Microsoft Word applications.
www.OnBarcode.com
PDF 417 Creation In C#
Using Barcode creation for Visual Studio .NET Control to generate, create PDF-417 2d barcode image in VS .NET applications.
www.OnBarcode.com
brackets around the parameters denote that they are optional; they are needed only if the associated CURSOR was declared with parameters. Listing 5-8 is short but powerful. In lines 11 through 16, I declare a CURSOR c_worker. Then, on line 19, I use the CURSOR FOR LOOP syntax to automatically OPEN the CURSOR and LOOP until there s no data found, placing any column values in an automatically declared record r_worker that is in scope only inside the FOR LOOP. If at least one row was retrieved from the database, the CURSOR FOR LOOP automatically CLOSEs the OPEN CURSOR when the LOOP ENDs. As I documented earlier in Table 3-1, I use the prefix c_ for cursors and the prefix r_ for records. This naming convention makes it easy to see exactly what is going on in PL/SQL. I told you PL/SQL s solution to the last exercise in 4 was going to get even better. As you can see, the CURSOR FOR LOOP represents some powerfully compact syntax! You can use a CURSOR FOR LOOP as long as you don t need the values of the fields in the automatically declared record outside the loop. And it will do you no good to declare the record outside the loop, because the CURSOR FOR LOOP will still declare its own. If you do need the cursor values beyond the fetch, you ll need to assign the record values to variables declared outside the loop or use a manual loop, as I did earlier in Listing 5-1. Enough talk it s time you put CURSOR FOR LOOP to work for you.
Drawing UCC - 12 In Java
Using Barcode generation for Java Control to generate, create UCC - 12 image in Java applications.
www.OnBarcode.com
Painting Code 3 Of 9 In Visual C#
Using Barcode generator for .NET Control to generate, create ANSI/AIM Code 39 image in VS .NET applications.
www.OnBarcode.com
It s Your Turn to Fetch Automatically
Generating Code 3/9 In None
Using Barcode generator for Office Excel Control to generate, create Code 39 Extended image in Office Excel applications.
www.OnBarcode.com
PDF417 Recognizer In None
Using Barcode reader for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
In the development process, you ll eventually need to test what you ve built with some realistic data; otherwise, you won t know how your code will perform in production. So your assignment here is to create a PL/SQL procedure that will populate table WORKER_T with test data. If you combine 100 last names, 100 first names, and 26 different middle initials, you get 260,000 entries for table WORKER_T. A quarter of a million entries in a table is a fair amount of data for testing. To help you out with this assignment, the create_relational.sql script created the TOP_100_FIRST_NAME, TOP_100_LAST_NAME, and A_THRU_Z tables for you when you ran it at the beginning of 2. I ve also placed these table scripts in the downloaded source code directory for 5, as top_100_first_name.tab, top_100_last_name.tab, and a_thru_z.tab, respectively. In order to populate table WORKER_T, I suggest you create a PL/SQL procedure that uses nested CURSOR FOR LOOPs to iterate through each table s entries, inserting an entry into the table for each loop, in the most nested FOR LOOP. Your executable code will look something like this: begin for r_last in c_last loop for r_first in c_first loop for r_middle in c_middle loop -- initialize the variables to be used in the insert statement here. insert into WORKER_T ... end loop; end loop; end loop; end; Of course, you ll need to supply values for other columns. For those, I suggest you do the following:
Reading PDF-417 2d Barcode In .NET Framework
Using Barcode decoder for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
EAN / UCC - 14 Creation In Visual Studio .NET
Using Barcode printer for Reporting Service Control to generate, create EAN 128 image in Reporting Service applications.
www.OnBarcode.com
CH A PT ER 5 N EXT PLEA SE, ON E RO W AT A TI ME!
UPC A Recognizer In Visual C#
Using Barcode reader for VS .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
Create Code39 In Java
Using Barcode drawer for Android Control to generate, create ANSI/AIM Code 39 image in Android applications.
www.OnBarcode.com
For id, call function WORKER_TS.get_id(). For worker_type_id, use an IF statement to flip back and forth between the ID values for an employee vs. contractor, on every other entry. For external_id, call function WORKER_TS.get_external_id(). For birth_date, call function DATES.random(1940, 1990); this will give you a randomly generated date between the years 1940 and 1990. For gender_id, use an IF statement to specify the correct ID value for the corresponding code found in the TOP_100_FIRST_NAME table. Add a variable to keep track of how many inserts you ve made, and then display that number on the screen when you re finished inserting. Save the script as worker_t_cursor_for_loop.ins, and then execute it. I know this is a hard assignment, but you have everything you need to get it done. Listing 5-9 is my solution to this exercise. When I ran this script on my computer, it inserted 260,000 rows in an average time of 98 seconds that s about 2,660 rows per second. Listing 5-9. Using CURSOR FOR LOOPs to Insert Test Data, worker_t_cursor_for_loop.ins 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 rem rem rem rem worker_t_cursor_for_loop.ins by Donald J. Bales on 12/15/2006 Seed the Worker table with the top 100 names 100 last x 100 first x 26 middle = 260,000 entries
Code 128 Code Set C Maker In Visual Basic .NET
Using Barcode printer for Visual Studio .NET Control to generate, create Code128 image in VS .NET applications.
www.OnBarcode.com
Encoding UPC-A Supplement 5 In None
Using Barcode printer for Online Control to generate, create Universal Product Code version A image in Online applications.
www.OnBarcode.com
set serveroutput on size 1000000; declare -- This is the cursor for the last names. cursor c_last is select last_name from TOP_100_LAST_NAME; -- This is the cursor for the first names. cursor c_first is select first_name, gender_code from TOP_100_FIRST_NAME; -- This is the cursor for the middle initials. cursor c_middle is select letter from A_THRU_Z; -- This is the number of seconds since midnight. -- I'll use it to profile my code's performance.
CHAPTER 5 NEXT PLEASE, ONE ROW AT A TIME!
028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073
n_start number := to_number(to_char(SYSDATE, 'SSSSS')); -- Here, I declare four pseudo-constants to hold the -- ID values from the code tables, rather than look -- them up repeatedly during the insert process. n_G_FEMALE GENDER_T.gender_id%TYPE; n_G_MALE GENDER_T.gender_id%TYPE; n_WT_CONTRACTOR WORKER_TYPE_T.worker_type_id%TYPE; n_WT_EMPLOYEE WORKER_TYPE_T.worker_type_id%TYPE; -- I'll use this to keep track of the number of -- rows inserted. n_inserted number := 0; -- Here, I declare a record anchored to the table so -- I can set the column values and then insert using -- the record. r_worker WORKER_T%ROWTYPE; begin -- Get the ID values for the codes n_G_FEMALE := GENDER_TS.get_id('F'); n_G_MALE := GENDER_TS.get_id('M'); n_WT_CONTRACTOR := WORKER_TYPE_TS.get_id('C'); n_WT_EMPLOYEE := WORKER_TYPE_TS.get_id('E'); -- Loop through the last names for r_last in c_last loop -- While looping through the last names, -- loop through the first names for r_first in c_first loop While looping through the last and first names, loop through the 26 letters in the English alphabet in order to get middle initials. As an alternative, I could have used a FOR LOOP: for i in ascii('A')..ascii('Z') loop for r_middle in c_middle loop -- Initialize the record -- Get the PK using the table's package r_worker.id := WORKER_TS.get_id(); ------
CH A PT ER 5 N EXT PLEA SE, ON E RO W AT A TI ME!
074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117
-- Flip flop from contractor if r_worker.worker_type_id = r_worker.worker_type_id := else r_worker.worker_type_id := end if;
to employee and back again n_WT_CONTRACTOR then n_WT_EMPLOYEE; n_WT_CONTRACTOR;
-- Get the External ID using the table's package r_worker.external_id := WORKER_TS.get_external_id(); -- The first, middle, and r_worker.first_name r_worker.middle_name r_worker.middle_name r_worker.last_name last names come from the cursors := r_first.first_name; := chr(i)||'.'; := r_middle.letter||'.'; := r_last.last_name;
-- Get the name using the table's package r_worker.name := WORKER_TS.get_formatted_name( r_worker.first_name, r_worker.middle_name, r_worker.last_name); -- Get a random date for a birth date r_worker.birth_date := DATES.random( to_number(to_char(SYSDATE, 'YYYY')) - 65, to_number(to_char(SYSDATE, 'YYYY')) - 18); -- Select the corresponding ID value if r_first.gender_code = 'F' then r_worker.gender_id := n_G_FEMALE; else r_worker.gender_id := n_G_MALE; end if; -- Insert the row into the database insert into WORKER_T values r_worker; -- Keep track of the number of inserts n_inserted := n_inserted + sql%rowcount; end loop; -- c_middle end loop; -- for i commit; -- commit every 26 rows end loop; -- c_first end loop; -- c_last
CHAPTER 5 NEXT PLEASE, ONE ROW AT A TIME!
118 119 120 121 122 123
-- Display the results pl(to_char(n_inserted)||' rows inserted in '|| (to_number(to_char(SYSDATE, 'SSSSS')) - n_start)|| ' seconds.'); end; /
I won t elaborate on my solution here, because I ve commented the code heavily. Notice that I ve added a variable to hold the start time in seconds, so I can test the performance of this solution against others. You ll see me profile code this way as we move forward. It s part of the testing process. The question now is, Can we make this PL/SQL procedure faster In Oracle8, some additional functionality was added to PL/SQL to improve performance. Let s look at one of those additions next.
Copyright © OnBarcode.com . All rights reserved.