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DECLARE section at the beginning of the PL/SQL block, unlike an implicit cursor, which you never refer to in the code. Once you declare your cursor, the explicit cursor will go through these steps: 1. The OPEN clause will identify the rows that are in the cursor and make them available for the PL/SQL program. 2. The FETCH command will retrieve data from the cursor into a specified variable. 3. The cursor should always be explicitly closed after your processing is completed. Listing A-4 shows how a cursor is first created and then used within a loop. Listing A-4. Using an Explicit Cursor DECLARE /* The cursor select_emp is explicitly declared */ CURSOR select_emp IS select emp_id, city from employees where city = 'DALLAS'; v_empno employees.emp_id%TYPE; v_empcity employees.city%TYPE; BEGIN /* The cursor select_emp is opened */ Open select _emp; LOOP /* The select_emp cursor data is fetched into v_empno variable */ FETCH select_emp into v_empno; EXIT WHEN select_emp%NOTFOUND; dbms_output.put_line(v_empno|| ','||v_empcity); END LOOP; /* The cursor select_emp is closed */ Close select_emp; END; /generating labels with barcode in c# using crystal reports, crystal reports barcode font, crystal reports barcode label printing, barcodes in crystal reports 2008, crystal report barcode formula, native barcode generator for crystal reports crack, asp.net mvc qr code generator, asp.net qr code, asp.net mvc qr code, asp.net qr code generator,
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In the example shown in Listing A-4, a special cursor attribute, %NOTFOUND, is used to indicate when the loop should terminate. Cursor attributes are very useful when you re dealing with explicit cursors. Here are the main cursor attributes: %ISOPEN is a Boolean attribute that evaluates to false after the SQL statement completes execution. It returns true as long as the cursor is open. %FOUND is a Boolean attribute that tests whether the SQL statement matches any row that is, whether the cursor has any more rows to fetch. %NOTFOUND is a Boolean attribute that tells you that the SQL statement doesn t match any row, meaning there are no more rows left to fetch. %ROWCOUNT gives you the number of rows the cursor has fetched so far.
In both of the previous examples, the additional code following the logical AND or OR to be run was a single command. Compound commands can be formed by surrounding the individual commands with curly braces. Such groupings can contain any amount of code, including output statements, control structures, assignments, or all of the above. As you ve seen before, the test command can be replaced with square brackets; the two forms of syntax are equivalent. This segment of code evaluates the expression within the square brackets and runs the compound statement if the expression evaluates as true. I have not noticed any significant performance differences between these two syntax types.
Figure 7-3. Project properties As discussed previously, it is a requirement to ensure that the DLL variant of the CRT is used. Therefore, modifying this setting can require modifications of the linker settings, too. Typically, you choose /MDd for the debug configuration and /MD for the release configuration. In contrast to the CRT choice, all other settings for projects and project items that are mentioned here should be specified equally for the build and the release configuration (and all other configurations you may have defined in your solution). My personal preference is to turn off generation of debug symbols with information for Edit and Continue at the project level, too. It does not make sense to generate debug symbols with Edit and Continue information for any of the source files whether they are compiled to native or managed code. This extra information would be an overhead without benefit, because Edit and Continue is not supported for managed and mixed-code assemblies
Normally when you use explicit cursors, cursors have to be opened, the data has to be fetched, and finally the cursor needs to be closed. A cursor FOR loop automatically performs the open, fetch, and close procedures, which simplifies your job. Listing A-5 shows an example that uses a cursor FOR loop construct. Listing A-5. Using the Cursor FOR Loop DECLARE CURSOR emp_cursor IS SELECT emp_id, emp_name, salary FROM employees; v_emp_info employees%RowType; Begin FOR emp_info IN emp_cursor LOOP dbms_output.put_line ('Employee id : '||emp_id||'Employee name : '|| emp_name||'Employee salary :'||salary); END LOOP; END; /